cytnx::linalg Namespace Reference

linear algebra related functions. More...

Functions
cytnx::UniTensor	Add (const cytnx::UniTensor &Lt, const cytnx::UniTensor &Rt)
	The addtion function between two UniTensor.
template<class T >
cytnx::UniTensor	Add (const T &lc, const cytnx::UniTensor &Rt)
	The addtion function between a template type and a UniTensor.
template<class T >
cytnx::UniTensor	Add (const cytnx::UniTensor &Lt, const T &rc)
	The addtion function between a UniTensor and a template type.
cytnx::UniTensor	Sub (const cytnx::UniTensor &Lt, const cytnx::UniTensor &Rt)
	The subtraction function between two UniTensor.
template<class T >
cytnx::UniTensor	Sub (const T &lc, const cytnx::UniTensor &Rt)
	The subtraction function between a UniTensor and a template type.
template<class T >
cytnx::UniTensor	Sub (const cytnx::UniTensor &Lt, const T &rc)
	The subtraction function between a UniTensor and a template type.
cytnx::UniTensor	Mul (const cytnx::UniTensor &Lt, const cytnx::UniTensor &Rt)
	The multiplication function between two UniTensor.
template<class T >
cytnx::UniTensor	Mul (const T &lc, const cytnx::UniTensor &Rt)
	The multiplication function between a UniTensor and a template type.
template<class T >
cytnx::UniTensor	Mul (const cytnx::UniTensor &Lt, const T &rc)
	The multiplication function between a UniTensor and a template type.
cytnx::UniTensor	Div (const cytnx::UniTensor &Lt, const cytnx::UniTensor &Rt)
	The division function between two UniTensor.
template<class T >
cytnx::UniTensor	Div (const T &lc, const cytnx::UniTensor &Rt)
	The division function between a UniTensor and a template type.
template<class T >
cytnx::UniTensor	Div (const cytnx::UniTensor &Lt, const T &rc)
	The division function between a UniTensor and a template type.
cytnx::UniTensor	Mod (const cytnx::UniTensor &Lt, const cytnx::UniTensor &Rt)
	element-wise modulo
template<class T >
cytnx::UniTensor	Mod (const T &lc, const cytnx::UniTensor &Rt)
	The modulo function between a UniTensor and a template type.
template<class T >
cytnx::UniTensor	Mod (const cytnx::UniTensor &Lt, const T &rc)
	The modulo function between a UniTensor and a template type.
std::vector< cytnx::UniTensor >	Svd (const cytnx::UniTensor &Tin, const bool &is_UvT=true)
	Perform Singular-Value decomposition on a UniTensor using divide-and-conquer method.
std::vector< cytnx::UniTensor >	Gesvd (const cytnx::UniTensor &Tin, const bool &is_U=true, const bool &is_vT=true)
	Perform Singular-Value decomposition on a UniTensor using ?gesvd method.
std::vector< cytnx::UniTensor >	Svd_truncate (const cytnx::UniTensor &Tin, const cytnx_uint64 &keepdim, const double &err=0, const bool &is_UvT=true, const bool &return_err=false)
	Perform Singular-Value decomposition on a UniTensor with truncation.
std::vector< cytnx::UniTensor >	Gesvd_truncate (const cytnx::UniTensor &Tin, const cytnx_uint64 &keepdim, const double &err=0, const bool &is_U=true, const bool &is_vT=true, const bool &return_err=false)
	Perform Singular-Value decomposition on a UniTensor with truncation.
std::vector< cytnx::UniTensor >	Hosvd (const cytnx::UniTensor &Tin, const std::vector< cytnx_uint64 > &mode, const bool &is_core=true, const bool &is_Ls=false, const std::vector< cytnx_int64 > &trucate_dim=std::vector< cytnx_int64 >())
template<typename T >
cytnx::UniTensor	ExpH (const cytnx::UniTensor &Tin, const T &a, const T &b=0)
	Perform the exponential function on a UniTensor, which the blocks are Hermitian matrix.
template<typename T >
cytnx::UniTensor	ExpM (const cytnx::UniTensor &Tin, const T &a, const T &b=0)
	Perform the exponential function on a UniTensor.
cytnx::UniTensor	ExpH (const cytnx::UniTensor &Tin)
	Perform the exponential function on a UniTensor, which the blocks are Hermitian matrix.
cytnx::UniTensor	ExpM (const cytnx::UniTensor &Tin)
	Perform the exponential function on a UniTensor.
cytnx::UniTensor	Trace (const cytnx::UniTensor &Tin, const cytnx_int64 &a=0, const cytnx_int64 &b=1)
cytnx::UniTensor	Trace (const cytnx::UniTensor &Tin, const std::string &a, const std::string &b)
	Perform trace over two legs of a UniTensor.
cytnx::UniTensor	Trace (const cytnx::UniTensor &Tin, const cytnx_int64 &a=0, const cytnx_int64 &b=1, const bool &by_label=false)
std::vector< cytnx::UniTensor >	Qr (const cytnx::UniTensor &Tin, const bool &is_tau=false)
	Perform the QR decomposition on a UniTensor.
std::vector< cytnx::UniTensor >	Qdr (const cytnx::UniTensor &Tin, const bool &is_tau=false)
	Perform the QDR decomposition on a UniTensor.
UniTensor	Pow (const UniTensor &Tin, const double &p)
	take power p on all the elements in UniTensor.
void	Pow_ (UniTensor &Tin, const double &p)
	Take power p on all the elements in UniTensor, inplacely.
Tensor	Add (const Tensor &Lt, const Tensor &Rt)
template<class T >
Tensor	Add (const T &lc, const Tensor &Rt)
	The addition function for Tensor.
template<class T >
Tensor	Add (const Tensor &Lt, const T &rc)
	The addition function for Tensor.
void	iAdd (Tensor &Lt, const Tensor &Rt)
	The addition function for Tensor, inplacely.
Tensor	Sub (const Tensor &Lt, const Tensor &Rt)
	The subtraction function for Tensor.
template<class T >
Tensor	Sub (const T &lc, const Tensor &Rt)
	The subtraction function for Tensor.
template<class T >
Tensor	Sub (const Tensor &Lt, const T &rc)
	The subtraction function for Tensor.
void	iSub (Tensor &Lt, const Tensor &Rt)
	The subtraction function for Tensot, inplscely.
Tensor	Mul (const Tensor &Lt, const Tensor &Rt)
	The multiplication function for Tensor.
template<class T >
Tensor	Mul (const T &lc, const Tensor &Rt)
	The multiplication function for Tensor.
template<class T >
Tensor	Mul (const Tensor &Lt, const T &rc)
	The multiplication function for Tensor.
void	iMul (Tensor &Lt, const Tensor &Rt)
	The multiplication function for Tensor, inplacely.
Tensor	Div (const Tensor &Lt, const Tensor &Rt)
	The division function for Tensor.
template<class T >
Tensor	Div (const T &lc, const Tensor &Rt)
	The division function for Tensor.
template<class T >
Tensor	Div (const Tensor &Lt, const T &rc)
	The division function for Tensor.
void	iDiv (Tensor &Lt, const Tensor &Rt)
	The inplace division function for Tensor, inplacely.
Tensor	Mod (const Tensor &Lt, const Tensor &Rt)
	The mod function for Tensor.
template<class T >
Tensor	Mod (const T &lc, const Tensor &Rt)
	The mod function for Tensor.
template<class T >
Tensor	Mod (const Tensor &Lt, const T &rc)
	The mod function for Tensor.
Tensor	Cpr (const Tensor &Lt, const Tensor &Rt)
	The comparison function for Tensor.
template<class T >
Tensor	Cpr (const T &lc, const Tensor &Rt)
	The comparison function for Tensor.
template<class T >
Tensor	Cpr (const Tensor &Lt, const T &rc)
	The comparison function for Tensor.
Tensor	Norm (const Tensor &Tl)
	Calculate the norm of a tensor.
Tensor	Det (const Tensor &Tl)
	Calculate the determinant of a tensor.
std::vector< Tensor >	Svd (const Tensor &Tin, const bool &is_UvT=true)
	Perform Singular-Value decomposition on a rank-2 Tensor (a matrix).
std::vector< Tensor >	Gesvd (const Tensor &Tin, const bool &is_U=true, const bool &is_vT=true)
	Perform Singular-Value decomposition on a rank-2 Tensor (a matrix).
std::vector< Tensor >	Svd_truncate (const Tensor &Tin, const cytnx_uint64 &keepdim, const double &err=0, const bool &is_UvT=true, const bool &return_err=false)
	Perform the truncate Singular-Value decomposition on a rank-2 Tensor (a matrix).
std::vector< Tensor >	Gesvd_truncate (const Tensor &Tin, const cytnx_uint64 &keepdim, const double &err=0, const bool &is_U=true, const bool &is_vT=true, const bool &return_err=false)
	Perform the truncate Singular-Value decomposition on a rank-2 Tensor (a matrix).
std::vector< Tensor >	Hosvd (const Tensor &Tin, const std::vector< cytnx_uint64 > &mode, const bool &is_core=true, const bool &is_Ls=false, const std::vector< cytnx_int64 > &trucate_dim=std::vector< cytnx_int64 >())
std::vector< Tensor >	Qr (const Tensor &Tin, const bool &is_tau=false)
	Perform QR decomposition on a rank-2 Tensor.
std::vector< Tensor >	Qdr (const Tensor &Tin, const bool &is_tau=false)
	Perform QDR decomposition on a rank-2 Tensor.
std::vector< Tensor >	Eigh (const Tensor &Tin, const bool &is_V=true, const bool &row_v=false)
	eigen-value decomposition for Hermitian matrix
std::vector< Tensor >	Eig (const Tensor &Tin, const bool &is_V=true, const bool &row_v=false)
	eigen-value decomposition for generic square matrix
Tensor	Trace (const Tensor &Tn, const cytnx_uint64 &axisA=0, const cytnx_uint64 &axisB=1)
	perform trace over index.
Tensor	Min (const Tensor &Tn)
	get the minimum element.
Tensor	Max (const Tensor &Tn)
	get the maximum element.
Tensor	Sum (const Tensor &Tn)
	get the sum of all the elements.
Tensor	Matmul (const Tensor &TL, const Tensor &TR)
	perform matrix multiplication on two tensors.
Tensor	Matmul_dg (const Tensor &Tl, const Tensor &Tr)
	perform matrix multiplication on two Tensors with one rank-1 and the other rank-2 where the rank-1 represent the diagonal elements of the specific tensor.
Tensor	InvM (const Tensor &Tin)
	Matrix inverse.
void	InvM_ (Tensor &Tin)
	inplace matrix inverse.
Tensor	Inv (const Tensor &Tin, const double &clip)
	Element-wise inverse with clip.
void	Inv_ (Tensor &Tin, const double &clip)
	inplace perform Element-wise inverse with clip.
Tensor	Conj (const Tensor &Tin)
	Conjugate all the element in Tensor.
void	Conj_ (Tensor &Tin)
	inplace perform Conjugate on all the element in Tensor.
Tensor	Exp (const Tensor &Tin)
	Exponential all the element in Tensor.
Tensor	Expf (const Tensor &Tin)
	Exponential all the element in Tensor.
void	Exp_ (Tensor &Tin)
	inplace perform Exponential on all the element in Tensor.
void	Expf_ (Tensor &Tin)
	inplace perform Exponential on all the element in Tensor.
Tensor	Pow (const Tensor &Tin, const double &p)
	take power p on all the elements in Tensor.
void	Pow_ (Tensor &Tin, const double &p)
	inplace perform power on all the elements in Tensor.
Tensor	Abs (const Tensor &Tin)
	Elementwise absolute value.
void	Abs_ (Tensor &Tin)
	inplace perform elementwiase absolute value. @This is just a inplace version of Abs. The input Tensor Tin will be modified.
Tensor	Diag (const Tensor &Tin)
	return a diagonal tensor with diagonal elements provided as Tin.
Tensor	Tensordot (const Tensor &Tl, const Tensor &Tr, const std::vector< cytnx_uint64 > &idxl, const std::vector< cytnx_uint64 > &idxr, const bool &cacheL=false, const bool &cacheR=false)
	perform tensor dot by sum out the indices assigned of two Tensors.
Tensor	Tensordot_dg (const Tensor &Tl, const Tensor &Tr, const std::vector< cytnx_uint64 > &idxl, const std::vector< cytnx_uint64 > &idxr, const bool &diag_L)
	perform tensor dot by sum out the indices assigned of two Tensors, with either one of them to be a rank-2 diagonal tensor represented by a rank-2 tensor.
Tensor	Outer (const Tensor &Tl, const Tensor &Tr)
	perform outer produces of two rank-1 Tensor.
Tensor	Kron (const Tensor &Tl, const Tensor &Tr, const bool &Tl_pad_left=false, const bool &Tr_pad_left=false)
	perform kronecker produces of two Tensor.
Tensor	Directsum (const Tensor &T1, const Tensor &T2, const std::vector< cytnx_uint64 > &shared_axes)
	perform directsum of two Tensor.
Tensor	Vectordot (const Tensor &Tl, const Tensor &Tr, const bool &is_conj=false)
	perform inner product of vectors
Tensor	Dot (const Tensor &Tl, const Tensor &Tr)
	dot product of two arrays.
std::vector< Tensor >	Tridiag (const Tensor &Diag, const Tensor &Sub_diag, const bool &is_V=true, const bool &is_row=false, bool throw_excp=false)
	perform diagonalization of symmetric tri-diagnoal matrix.
template<typename T >
Tensor	ExpH (const Tensor &in, const T &a, const T &b=0)
	perform matrix exponential for Hermitian matrix
Tensor	ExpH (const Tensor &in)
template<typename T >
Tensor	ExpM (const Tensor &in, const T &a, const T &b=0)
	perform matrix exponential for generic matrix
Tensor	ExpM (const Tensor &in)
	perform matrix exponential for generic matrix
std::vector< Tensor >	Arnoldi (LinOp *Hop, const Tensor &Tin=Tensor(), const std::string which="LM", const cytnx_uint64 &maxiter=10000, const cytnx_double &cvg_crit=1.0e-9, const cytnx_uint64 &k=1, const bool &is_V=true, const bool &verbose=false)
	perform Arnoldi for matrices or linear function.
std::vector< Tensor >	Lanczos (LinOp *Hop, const Tensor &Tin=Tensor(), const std::string method="Gnd", const double &CvgCrit=1.0e-14, const unsigned int &Maxiter=10000, const cytnx_uint64 &k=1, const bool &is_V=true, const bool &is_row=false, const cytnx_uint32 &max_krydim=0, const bool &verbose=false)
	perform Lanczos for hermitian/symmetric matrices or linear function.
std::vector< UniTensor >	Lanczos (LinOp *Hop, const UniTensor &Tin=UniTensor(), const std::string method="Gnd", const double &CvgCrit=1.0e-14, const unsigned int &Maxiter=10000, const cytnx_uint64 &k=1, const bool &is_V=true, const bool &is_row=false, const cytnx_uint32 &max_krydim=4, const bool &verbose=false)
	perform Lanczos for hermitian/symmetric matrices or linear function.
std::vector< Tensor >	Lanczos_ER (LinOp *Hop, const cytnx_uint64 &k=1, const bool &is_V=true, const cytnx_uint64 &maxiter=10000, const double &CvgCrit=1.0e-14, const bool &is_row=false, const Tensor &Tin=Tensor(), const cytnx_uint32 &max_krydim=4, const bool &verbose=false)
	perform Lanczos for hermitian/symmetric matrices or linear function.
std::vector< Tensor >	Lanczos_Gnd (LinOp *Hop, const double &CvgCrit=1.0e-14, const bool &is_V=true, const Tensor &Tin=Tensor(), const bool &verbose=false, const unsigned int &Maxiter=100000)
	perform Lanczos for hermitian/symmetric matrices or linear function to get ground state and lowest eigen value
std::vector< UniTensor >	Lanczos_Gnd_Ut (LinOp *Hop, const UniTensor &Tin, const double &CvgCrit=1.0e-14, const bool &is_V=true, const bool &verbose=false, const unsigned int &Maxiter=100000)
	perform Lanczos for hermitian/symmetric matrices or linear function to get ground state and lowest eigen value
std::vector< Tensor >	Lstsq (const Tensor &A, const Tensor &b, const float &rcond=-1)
	Return the least-squares solution to a linear matrix equation.
Tensor	Axpy (const Scalar &a, const Tensor &x, const Tensor &y=Tensor())
	Blas Axpy, performing \( a\textbf{x} + \textbf{y} \), inplacely.
void	Axpy_ (const Scalar &a, const Tensor &x, Tensor &y)
	Blas Axpy, performing \( \textbf{y} = a\textbf{x} + \textbf{y} \), inplacely.
Tensor	Ger (const Tensor &x, const Tensor &y, const Scalar &a=Scalar())
	Blas Ger, performing return = a*vec(x)*vec(y)^T.
void	Gemm_ (const Scalar &a, const Tensor &x, const Tensor &y, const Scalar &b, Tensor &c)
	Blas Gemm, performing \( \textbf{c} = a\textbf{x}\textbf{y} + b\textbf{c} \), inplacely.
Tensor	Gemm (const Scalar &a, const Tensor &x, const Tensor &y)
	Blas Gemm, performing \( a\textbf{x}\textbf{y} -> \) return.

Detailed Description

linear algebra related functions.

This namespace contains all the linear algebra related functions. For example, the matrix multiplication, the singular value decomposition, etc. If the linear algebra can only perfom on a matrix, then in most cases,

1. If the object is Tensor, then it need to be rank-2.
2. If the object is UniTensor, then the result will depend on the UniTensor's rowrank.

Function Documentation

Abs()

Tensor cytnx::linalg::Abs

(

const Tensor &

Tin

)

Elementwise absolute value.

This function will perform Elementwise absolute value on all the elements in Tensor Tin. That is, the output will be:

\[ T_{o}[i] = |T_{i}[i]| \]

Parameters

[in]

Tin

tensor.

Returns

[Tensor]

Abs_()

void cytnx::linalg::Abs_

(

Tensor &

Tin

)

inplace perform elementwiase absolute value. @This is just a inplace version of Abs. The input Tensor Tin will be modified.

Parameters

[in]

Tin,the

input Tensor.

Note

on return, the elements in Tin will be modified to it's absolute value. Note that if the input tensor is complex, it will be modified to real type.

Add() [1/6]

cytnx::UniTensor cytnx::linalg::Add	(	const cytnx::UniTensor &	Lt,
		const cytnx::UniTensor &	Rt
	)

The addtion function between two UniTensor.

This is the addtion function for UniTensor. It will perform the element-wise addtion. That means if the left UniTensor Lt is given as \( T_L \) and the right UniTensor Rt is given as \( T_R \), then the result will be:

\[ T_o[i] = T_L[i] + T_R[i], \]

where \( T_L[i] \) and \( T_R[i] \) are the elements in the UniTensor \( T_L \) and \( T_R \). It will perform the element-wise addtion and note that it will return a new UniTensor object.

Parameters

[in]	Lt	The left UniTensor.
[in]	Rt	The right UniTensor.

Returns

The result UniTensor.

Precondition

Lt and Rt must have the same shape.

See also

UniTensor::Add(const UniTensor &Rt) const, operator+(const UniTensor &Lt, const UniTensor &Rt)

Add() [2/6]

template<class T >

cytnx::UniTensor cytnx::linalg::Add	(	const cytnx::UniTensor &	Lt,
		const T &	rc
	)

The addtion function between a UniTensor and a template type.

This is the addtion function for UniTensor. It will add the UniTensor and a template type together and add every element in the UniTensor with the template type. That means if the UniTensor Lt is given as \( T_i \) and the template type rc is given as \( c \), then the result will be:

\[ T_o[i] = T_i[i] + c, \]

where \( T_i[i] \) and \( T_o[i] \) are the elements in the UniTensor \( T_i \) and \( T_o \).

Parameters

[in]	Lt	The left UniTensor.
[in]	rc	The right template type. supported type: Scalar, cytnx::cytnx_complex128, cytnx::cytnx_complex64, cytnx::cytnx_double, cytnx::cytnx_float, cytnx::cytnx_int64, cytnx::cytnx_uint64, cytnx::cytnx_int32, cytnx::cytnx_uint32, cytnx::cytnx_int16, cytnx::cytnx_uint16, cytnx::cytnx_bool.

Returns

The result UniTensor.

Precondition

The supported template type shown above.

Note

The inpute template type rc will be casted to the same type as the UniTensor Lt.

See also

operator+(const UniTensor &Lt, const T &rc), Add(const T &lc, const cytnx::UniTensor &Rt)

Add() [3/6]

template<class T >

cytnx::UniTensor cytnx::linalg::Add	(	const T &	lc,
		const cytnx::UniTensor &	Rt
	)

The addtion function between a template type and a UniTensor.

This is the addtion function for UniTensor. It will add the UniTensor and a template type together and add every element in the UniTensor with the template type. That means if the template type lc is given as \( c \) and the UniTensor Rt is given as \( T_i \), then the result will be:

\[ T_o[i] = c + T_i[i], \]

where \( T_i[i] \) and \( T_o[i] \) are the elements in the UniTensor \( T_i \) and \( T_o \).

Parameters

[in]	lc	The left template type. supported type: Scalar, cytnx::cytnx_complex128, cytnx::cytnx_complex64, cytnx::cytnx_double, cytnx::cytnx_float, cytnx::cytnx_int64, cytnx::cytnx_uint64, cytnx::cytnx_int32, cytnx::cytnx_uint32, cytnx::cytnx_int16, cytnx::cytnx_uint16, cytnx::cytnx_bool.
[in]	Rt	The right UniTensor.

Returns

The result UniTensor.

Precondition

The supported template type shown above.

Note

The inpute template type lc will be casted to the same type as the UniTensor Rt.

See also

operator+(const T &lc, const UniTensor &Rt), Add(const cytnx::UniTensor &Lt, const cytnx::UniTensor &Rt)

Add() [4/6]

template<class T >

Tensor cytnx::linalg::Add	(	const T &	lc,
		const Tensor &	Rt
	)

The addition function for Tensor.

This is the addtion function between a Tensor and a template type. It will perform the element-wise addtion. That means if the template type lc is given as \( c \) and the Tensor Rt is given as \( T_R \), then the result will be:

\[ T_o[i] = c + T_L[i], \]

where \( T_R[i] \) is the elements in the Tensor \( T_R \). It will perform the element-wise addtion and note that it will return a new Tensor object.

Parameters

[in]	lc	The left template type.
[in]	Rt	The right Tensor.

Returns

The result Tensor.

See also

Add(const Tensor &Lt, const Tensor &Rt), Add(const Tensor &Lt, const T &rc), iAdd(Tensor &Lt, const Tensor &Rt), operator+(const Tensor &Lt, const Tensor &Rt)

Add() [5/6]

template<class T >

Tensor cytnx::linalg::Add	(	const Tensor &	Lt,
		const T &	rc
	)

The addition function for Tensor.

This is the addtion function between a Tensor and a template type. It will perform the element-wise addtion. That means if the Tensor Lt is given as \( T_L \) and the template type rc is given as \( c \), then the result will be:

\[ T_o[i] = T_L[i] + c, \]

where \( T_L[i] \) is the elements in the Tensor \( T_L \). It will perform the element-wise addtion and note that it will return a new Tensor object.

Parameters

[in]	Lt	The left Tensor.
[in]	rc	The right template type.

Returns

The result Tensor.

See also

Add(const Tensor &Lt, const Tensor &Rt), Add(const T &lc, const Tensor &Rt), iAdd(Tensor &Lt, const Tensor &Rt), operator+(const Tensor &Lt, const Tensor &Rt)

Add() [6/6]

Tensor cytnx::linalg::Add	(	const Tensor &	Lt,
		const Tensor &	Rt
	)

@bridf The addition function for Tensor.

This is the addtion function between two Tensor. It will perform the element-wise addtion. That means if the left Tensor Lt is given as \( T_L \) and the right Tensor Rt is given as \( T_R \), then the result will be:

\[ T_o[i] = T_L[i] + T_R[i], \]

where \( T_L[i] \) and \( T_R[i] \) are the elements in the Tensor \( T_L \) and \( T_R \). It will perform the element-wise addtion and note that it will return a new Tensor object.

Parameters

[in]	Lt	The left Tensor.
[in]	Rt	The right Tensor.

Returns

The result Tensor.

Precondition

The shape of Lt and Rt must be the same.

See also

Add(const T &lc, const Tensor &Rt), Add(const Tensor &Lt, const T &rc), iAdd(Tensor &Lt, const Tensor &Rt), operator+(const Tensor &Lt, const Tensor &Rt)

Arnoldi()

std::vector< Tensor > cytnx::linalg::Arnoldi	(	LinOp *	Hop,
		const Tensor &	Tin = Tensor(),
		const std::string	which = "LM",
		const cytnx_uint64 &	maxiter = 10000,
		const cytnx_double &	cvg_crit = 1.0e-9,
		const cytnx_uint64 &	k = 1,
		const bool &	is_V = true,
		const bool &	verbose = false
	)

perform Arnoldi for matrices or linear function.

This function calculate the eigen value problem using Arnoldi algorithm.

Parameters

[in]	Hop	the Linear Operator defined by LinOp class or it's inheritance (see LinOp).
[in]	Tin	the initial vector, this should be rank-1.
[in]	which	which order eigenvlues and corresponding eigenvectors should be find, the supported options are: 'LM' : largest magnitude 'LR' : largest real part 'LI' : largest imaginary part 'SM' : smallest magnitude 'SR' : smallest real part 'SI' : smallest imaginary part
[in]	maxiter	the maximum interation steps for each k.
[in]	cvg_crit	the convergence criterion of the energy.
[in]	k	the number of lowest k eigen values.
[in]	is_V	if set to true, the eigen vectors will be returned.
[in]	verbose	print out iteration info.

Returns

[eigvals (Tensor), eigvecs (Tensor)(option)]

Note

To use, define a linear operator with LinOp class either by assign a custom function or create a class that inherit LinOp (see LinOp for further details)

Axpy()

Tensor cytnx::linalg::Axpy	(	const Scalar &	a,
		const Tensor &	x,
		const Tensor &	y = Tensor()
	)

Blas Axpy, performing \( a\textbf{x} + \textbf{y} \), inplacely.

This function performs

\[ a\textbf{x} + \textbf{y}, \]

where \( \textbf{x},\textbf{y} \) are Tensor and \( a \) is a Scalar. The dtype of return Tensor will be the strongest among x, y and a.

Parameters

[in]	a	Scalar.
[in]	x	Tensor, can be any rank
[in]	y	Tensor, can be any rank

Returns

[Tensor] If \( \textbf{y} \) is not specify, then it performs \( a\textbf{x} \) -> return

Note

This will return a new tensor.

Axpy_()

void cytnx::linalg::Axpy_	(	const Scalar &	a,
		const Tensor &	x,
		Tensor &	y
	)

Blas Axpy, performing \( \textbf{y} = a\textbf{x} + \textbf{y} \), inplacely.

This function performs

\[ \textbf{y} = a\textbf{x} + \textbf{y}, \]

where \( \textbf{x},\textbf{y} \) are Tensor and a is a Scalar. The dtype of return Tensor will be the strongest among x, y and a.

Parameters

[in]	a	Scalar.
[in]	x	Tensor, can be any rank
[in]	y	Tensor, can be any rank

Returns

[Tensor] If \( \textbf{y} \) is not specify, then it performs \( a\textbf{x} \) -> return

Note

Compared to Axpy(const Scalar &a, const Tensor &x, const Tensor &y = Tensor()), this function will perform inplacely.

Conj()

Tensor cytnx::linalg::Conj

(

const Tensor &

Tin

)

Conjugate all the element in Tensor.

This function take the complex conjugate of all the elements in Tensor Tin. That is, the output will be:

\[ T_{o}[i] = T_{in}[i]^* \]

Furthermore,

1. if the input Tensor is complex, then return a new Tensor with all the elements are conjugated.
2. if the input Tensor is real, then return a copy of input Tensor.

   Parameters

   [in]

   Tin

   a Tensor

   Returns

   [Tensor]

Conj_()

void cytnx::linalg::Conj_

(

Tensor &

Tin

)

inplace perform Conjugate on all the element in Tensor.

This function take the complex conjugate of all the elements in Tensor Tin. This function is just a inplace version of Conj.

Note

1. if the input Tensor is complex, the elements of input Tensor will all be conjugated.
2. if the input Tensor is real, then nothing act.

Cpr() [1/3]

template<class T >

Tensor cytnx::linalg::Cpr	(	const T &	lc,
		const Tensor &	Rt
	)

The comparison function for Tensor.

This is the comparison function between a Tensor and a template type. It will perform the element-wise comparison. That means if the left template type lc is given as \( c \) and the right Tensor Rt is given as \( T_R \), then the result will be:

\[ T_o[i] = \left\{\begin{array}{ll} 1, & \text{if } c=T_R[i]\\ 0, & \text{else} \end{array}\right. \]

where \( T_o[i]\), \( c \) and \( T_R[i] \) are the elements in the Tensor \( T_o\), \( c \) and \( T_R \) and \( T_o[i] \) is the output Tensor which is a boolean type (see cytnx::Type). It will perform the element-wise comparison and note that it will return a new Tensor object.

Parameters

[in]	lc	The left template type.
[in]	Rt	The right Tensor.

Returns

The result Tensor.

See also

Cpr(const Tensor &Lt, const Tensor &Rt), Cpr(const Tensor &Lt, const T &rc)

Cpr() [2/3]

template<class T >

Tensor cytnx::linalg::Cpr	(	const Tensor &	Lt,
		const T &	rc
	)

The comparison function for Tensor.

This is the comparison function between a Tensor and a template type. It will perform the element-wise comparison. That means if the left Tensor Lt is given as \( T_L \) and the right template type rc is given as \( c \), then the result will be:

\[ T_o[i] = \left\{\begin{array}{ll} 1, & \text{if } T_L[i]=c\\ 0, & \text{else} \end{array}\right. \]

where \( T_o[i]\), \( T_L[i] \) and \( c \) are the elements in the Tensor \( T_o\), \( T_L \) and \( c \) and \( T_o[i] \) is the output Tensor which is a boolean type (see cytnx::Type). It will perform the element-wise comparison and note that it will return a new Tensor object.

Parameters

[in]	Lt	The left Tensor.
[in]	rc	The right template type.

Returns

The result Tensor.

See also

Cpr(const Tensor &Lt, const Tensor &Rt), Cpr(const T &lc, const Tensor &Rt)

Cpr() [3/3]

Tensor cytnx::linalg::Cpr	(	const Tensor &	Lt,
		const Tensor &	Rt
	)

The comparison function for Tensor.

This is the comparison function between two Tensor. It will perform the element-wise comparison. That means if the left Tensor Lt is given as \( T_L \) and the right Tensor Rt is given as \( T_R \), then the result will be:

\[ T_o[i] = \left\{\begin{array}{ll} 1, & \text{if } T_L[i]=T_R[i]\\ 0, & \text{else} \end{array}\right. \]

where \( T_o[i]\), \( T_L[i] \) and \( T_R[i] \) are the elements in the Tensor \( T_o\), \( T_L \) and \( T_R \) and \( T_o[i] \) is the output Tensor which is a boolean type (see cytnx::Type). It will perform the element-wise comparison and note that it will return a new Tensor object.

Parameters

[in]	Lt	The left Tensor.
[in]	Rt	The right Tensor.

Returns

The result Tensor.

Precondition

The input tensors Lt and Rt should have the same shape.

See also

Cpr(const T &lc, const Tensor &Rt), Cpr(const Tensor &Lt, const T &rc)

Det()

Tensor cytnx::linalg::Det

(

const Tensor &

Tl

)

Calculate the determinant of a tensor.

This function will calculate the determinant of a square matrix . That means the input tensor should be a rank-2 tensor with shape (N,N).

Parameters

[in]

Tl

input a Tensor with shape (N,N)

Returns

Tensor

Precondition

the input tensor should be a rank-2 tensor with shape (N,N). (a square matrix)

Diag()

Tensor cytnx::linalg::Diag

(

const Tensor &

Tin

)

return a diagonal tensor with diagonal elements provided as Tin.

Returns

[Tensor]

This function will return a diagonal tensor with diagonal elements provided as Tin. Furthermore, the return Tensor will be rank-2, with shape=(L, L); where L is the number of elements in Tin.

Precondition

Tin should be a rank-2 Tensor.

Directsum()

Tensor cytnx::linalg::Directsum	(	const Tensor &	T1,
		const Tensor &	T2,
		const std::vector< cytnx_uint64 > &	shared_axes
	)

perform directsum of two Tensor.

The function assume two tensor has the same rank, and axes indicated in <shared_axes> are the same for both T1 and T2. The out put tensors will have same rank as T1 and T2, with the dimension of rest of the axes being the sum of dimensions of T1 and T2. e.g., the out put shape = (i1+i2,j1+j2, share_axis_1, k1+k2, share_axis_2, ...); where T1.shape = (i1,j1,share_axis_1,k1,share_axis_2 ...) and T2.shape = (i2,j2,share_axis_1,k2,share_axis_2 ...)

Parameters

[in]	T1	rank-n Tensor #1
[in]	T2	rank-n Tensor #2
[in]	shared_axes	The axes that are shared by two tensors

Returns

[Tensor]

Precondition

two tensor should on same device.

Div() [1/6]

cytnx::UniTensor cytnx::linalg::Div	(	const cytnx::UniTensor &	Lt,
		const cytnx::UniTensor &	Rt
	)

The division function between two UniTensor.

This is the division function for UniTensor. It will divide the left UniTensor and the right UniTensor together. It will divide every element in the left UniTensor with the right UniTensor. That means if the left UniTensor Lt is given as \( T_L \) and the right UniTensor Rt is given as \( T_R \), then the result will be:

\[ T_o[i] = T_L[i] \div T_R[i], \]

where \( T_L[i] \) and \( T_R[i] \) are the elements in the UniTensor \( T_L \) and \( T_R \). It will perform the element-wise division and note that it will return a new UniTensor object.

Parameters

[in]	Lt	The left UniTensor.
[in]	Rt	The right UniTensor.

Returns

The result UniTensor.

Precondition

Lt and Rt must have the same shape.

See also

UniTensor::Div(const UniTensor &Rt) const, operator/(const UniTensor &Lt, const UniTensor &Rt)

Div() [2/6]

template<class T >

cytnx::UniTensor cytnx::linalg::Div	(	const cytnx::UniTensor &	Lt,
		const T &	rc
	)

The division function between a UniTensor and a template type.

This is the division function for UniTensor. It will divide the UniTensor and a template type together. It will divide every element in the UniTensor with the template type. That means if the UniTensor Lt is given as \( T_i \) and the template type rc is given as \( c \), then the result will be:

\[ T_o[i] = T_i[i] \div c, \]

where \( T_i[i] \) and \( T_o[i] \) are the elements in the UniTensor \( T_i \) and \( T_o \).

Parameters

[in]	Lt	The left UniTensor.
[in]	rc	The right template type. supported type: Scalar, cytnx::cytnx_complex128, cytnx::cytnx_complex64, cytnx::cytnx_double, cytnx::cytnx_float, cytnx::cytnx_int64, cytnx::cytnx_uint64, cytnx::cytnx_int32, cytnx::cytnx_uint32, cytnx::cytnx_int16, cytnx::cytnx_uint16, cytnx::cytnx_bool.

Returns

The result UniTensor.

Precondition

The supported template type shown above.

Note

1. The inpute template type rc will be casted to the same type as the UniTensor Lt.
2. The division by zero is not allowed.

See also

operator/(const UniTensor &Lt, const T &rc), Div(const cytnx::UniTensor &Lt, const T &rc)

Div() [3/6]

template<class T >

cytnx::UniTensor cytnx::linalg::Div	(	const T &	lc,
		const cytnx::UniTensor &	Rt
	)

The division function between a UniTensor and a template type.

This is the division function for UniTensor. It will divide the UniTensor and a template type together. It will divide every element in the UniTensor with the template type. That means if the template type lc is given as \( c \) and the UniTensor Rt is given as \( T_i \), then the result will be:

\[ T_o[i] = c \div T_i[i], \]

where \( T_i[i] \) and \( T_o[i] \) are the elements in the UniTensor \( T_i \) and \( T_o \).

Parameters

[in]	Lt	The left UniTensor.
[in]	rc	The right template type. supported type: Scalar, cytnx::cytnx_complex128, cytnx::cytnx_complex64, cytnx::cytnx_double, cytnx::cytnx_float, cytnx::cytnx_int64, cytnx::cytnx_uint64, cytnx::cytnx_int32, cytnx::cytnx_uint32, cytnx::cytnx_int16, cytnx::cytnx_uint16, cytnx::cytnx_bool.

Returns

The result UniTensor.

Precondition

The supported template type shown above.

Note

1. The inpute template type lc will be casted to the same type as the UniTensor Rt.
2. The division by zero is not allowed.

See also

operator/(const T &lc, const UniTensor &Rt), Div(const T &lc, const cytnx::UniTensor &Rt)

Div() [4/6]

template<class T >

Tensor cytnx::linalg::Div	(	const T &	lc,
		const Tensor &	Rt
	)

The division function for Tensor.

This is the division function between a Tensor and a template type. It will perform the element-wise division. That means if the left template type lc is given as \( c \) and the right Tensor Rt is given as \( T_R \), then the result will be:

\[ T_o[i] = c / T_R[i] \]

where \( T_L[i] \) is the elements in the Tensor \( T_L \). It will perform the element-wise division and note that it will return a new Tensor object.

Parameters

[in]	lc	The left template type.
[in]	Rt	The right Tensor.

Returns

The result Tensor.

Precondition

the right tensor Rt should not contain any zero element.

See also

Div(const Tensor &Lt, const Tensor &Rt), Div(const Tensor &Lt, const T &rc), iDiv(Tensor &Lt, const Tensor &Rt), operator/(const Tensor &Lt, const Tensor &Rt)

Div() [5/6]

template<class T >

Tensor cytnx::linalg::Div	(	const Tensor &	Lt,
		const T &	rc
	)

The division function for Tensor.

This is the division function between a Tensor and a template type. It will perform the element-wise division. That means if the left Tensor Lt is given as \( T_L \) and the right template type rc is given as \( c \), then the result will be:

\[ T_o[i] = T_L[i] / c \]

where \( T_L[i] \) is the elements in the Tensor \( T_L \). It will perform the element-wise division and note that it will return a new Tensor object.

Parameters

[in]	Lt	The left Tensor.
[in]	rc	The right template type.

Returns

The result Tensor.

Precondition

the right template type rc should not be zero.

See also

Div(const Tensor &Lt, const Tensor &Rt), Div(const T &lc, const Tensor &Rt), iDiv(Tensor &Lt, const Tensor &Rt), operator/(const Tensor &Lt, const Tensor &Rt)

Div() [6/6]

Tensor cytnx::linalg::Div	(	const Tensor &	Lt,
		const Tensor &	Rt
	)

The division function for Tensor.

This is the division function between two Tensor. It will perform the element-wise division. That means if the left Tensor Lt is given as \( T_L \) and the right Tensor Rt is given as \( T_R \), then the result will be:

\[ T_o[i] = T_L[i] / T_R[i] \]

where \( T_L[i] \) and \( T_R[i] \) are the elements in the Tensor \( T_L \) and \( T_R \). It will perform the element-wise division and note that it will return a new Tensor object.

Parameters

[in]	Lt	The left Tensor.
[in]	Rt	The right Tensor.

Returns

The result Tensor.

Precondition

the right Tensor Rt should not contain any zero element.

See also

Div(const T &lc, const Tensor &Rt), Div(const Tensor &Lt, const T &rc), iDiv(Tensor &Lt, const Tensor &Rt), operator/(const Tensor &Lt, const Tensor &Rt)

Dot()

Tensor cytnx::linalg::Dot	(	const Tensor &	Tl,
		const Tensor &	Tr
	)

dot product of two arrays.

1. if both Tl and Tr are 1d arrays, it is inner product of vectors (no complex conj), it calls linalg.Vectordot with is_conj=false.
2. if both Tl and Tr are 2d arrays, it calls linalg.Matmul to compute the matrix multiplication
3. if Tl is Nd array (with N>=2, and Tr is 1-D array, it is sum product over the last axis of a with b

   Parameters

   [in]	Tl	Tensor #1
   [in]	Tr	Tensor #2

   Returns

   [Tensor]

   Note

   performance tune: This function have better performance when two arrays with same types, and are one of following type: cytnx_double, cytnx_float, cytnx_complex64 or cytnx_complex128. [Python] In Python API, operator@ is overloaded as a shorthand of linalg::Dot.

Eig()

std::vector< Tensor > cytnx::linalg::Eig	(	const Tensor &	Tin,
		const bool &	is_V = true,
		const bool &	row_v = false
	)

eigen-value decomposition for generic square matrix

This function will perform eigen-value decomposition for generic square matrix. Given a matrix Tin as \( M \), then the result will be:

\[ M = V^{-1} D V, \]

where \( V \) is a invertible matrix contains the eigen vectors, and \( D \) is a diagonal matrix contains the eigen values.

Parameters

[in]	Tin	A square matrix (a rank-2 Tensor)
[in]	is_V	whether need to return the eigen vectors.
[in]	row_V	if set to ture, the return eigen vectors will be row form.

Returns

[std::vector<Tensors>], the first tensor is the eigen values, a 1-d tensor (vector). The second tensor is the eigen vectors, a 2-d tensor (matrix). This tensor will only return when is_V = true. Furthermore, if row_V = true, then the eigen vectors will be row form. Otherwise, the eigen vectors will be column form.

Precondition

the Tin should be a square matrix.

Eigh()

std::vector< Tensor > cytnx::linalg::Eigh	(	const Tensor &	Tin,
		const bool &	is_V = true,
		const bool &	row_v = false
	)

eigen-value decomposition for Hermitian matrix

This function will perform eigen-value decomposition for Hermitian matrix. Given a matrix Tin as \( M \), then the result will be:

\[ M = V^\dagger D V, \]

where \( V \) is a unitary matrix contains the eigen vectors, and \( D \) is a diagonal matrix contains the eigen values.

Parameters

[in]	Tin	a Tensor , it should be a rank-2 tensor (matrix)
[in]	is_V	whether need to return the eigen vectors.
[in]	row_V	if set to ture, the return eigen vectors will be row form.

Returns

[std::vector<Tensors>], the first tensor is the eigen values, a 1-d tensor (vector). The second tensor is the eigen vectors, a 2-d tensor (matrix). This tensor will only return when is_V = true. Furthermore, if row_V = true, then the eigen vectors will be row form. Otherwise, the eigen vectors will be column form.

Precondition

the Tin should be a Hermitian matrix.

Warning

If Tin is not a Hermitian matrix, the result will be undefined.

Exp()

Tensor cytnx::linalg::Exp

(

const Tensor &

Tin

)

Exponential all the element in Tensor.

This function will perform Exponential on all the elements in Tensor Tin. That is, the output will be:

\[ T_{o}[i] = e^{T_{i}[i]} \]

Note that it will cast to Double type or ComplexDouble type.

Parameters

[in]

Tin

a Tensor

Returns

[Double Tensor] or [ComplexDouble Tensor]

Exp_()

void cytnx::linalg::Exp_

(

Tensor &

Tin

)

inplace perform Exponential on all the element in Tensor.

This function will perform Exponential on all the elements in Tensor Tin. Furthermore,

1. on return, the elements in Tin will be modified to it's exponetial value.
2. For Real, if the type is not Double, change the type of the input tensor to Double.
3. For Complex, if input is ComplexFloat, promote to ComplexDouble.

   Parameters

   [in]

   Tin,the

   input Tensor.

Expf()

Tensor cytnx::linalg::Expf

(

const Tensor &

Tin

)

Exponential all the element in Tensor.

This function will perform Exponential on all the elements in Tensor Tin. That is, the output will be:

\[ T_{o}[i] = e^{T_{i}[i]} \]

Note that it will cast to Float type or ComplexFloat type.

Parameters

[in]

Tin

a Tensor

Returns

[Float Tensor] or [ComplexFloat Tensor]

Expf_()

void cytnx::linalg::Expf_

(

Tensor &

Tin

)

inplace perform Exponential on all the element in Tensor.

This function will perform Exponential on all the elements in Tensor Tin. Furthermore,

1. on return, the elements in Tin will be modified to it's exponetial value.
2. For Real, if the type is not Float, change the type of the input tensor to Float.
3. For Complex, if input is ComplexDouble, promote to ComplexFloat.

   Parameters

   [in]

   Tin,the

   input Tensor.

ExpH() [1/4]

cytnx::UniTensor cytnx::linalg::ExpH

(

const cytnx::UniTensor &

Tin

)

Perform the exponential function on a UniTensor, which the blocks are Hermitian matrix.

This function performs the exponential function on a UniTensor Tin, which the blocks are Hermitian matrix. For more details, please refer to the documentation of the function ExpH(const Tensor &Tin)

See also

ExpH(const Tensor &Tin)

ExpH() [2/4]

template<typename T >

cytnx::UniTensor cytnx::linalg::ExpH	(	const cytnx::UniTensor &	Tin,
		const T &	a,
		const T &	b = 0
	)

Perform the exponential function on a UniTensor, which the blocks are Hermitian matrix.

This function performs the exponential function on a UniTensor Tin, which the blocks are Hermitian matrix. For more details, please refer to the documentation of the function ExpH(const Tensor &Tin, const T &a, const T &b).

See also

ExpH(const Tensor &Tin, const T &a, const T &b)

ExpH() [3/4]

Tensor cytnx::linalg::ExpH

(

const Tensor &

in

)

ExpH() [4/4]

template<typename T >

Tensor cytnx::linalg::ExpH	(	const Tensor &	in,
		const T &	a,
		const T &	b = 0
	)

perform matrix exponential for Hermitian matrix

Parameters

in	input Tensor, should be Hermitian
a	rescale factor
b	bias

Returns

[Tensor]

description: perform matrix exponential with \(O = \exp{aM + b}\).

ExpM() [1/4]

cytnx::UniTensor cytnx::linalg::ExpM

(

const cytnx::UniTensor &

Tin

)

Perform the exponential function on a UniTensor.

This function performs the exponential function on a UniTensor Tin. For more details, please refer to the documentation of the function ExpM(const Tensor &Tin)

See also

ExpM(const Tensor &Tin)

ExpM() [2/4]

template<typename T >

cytnx::UniTensor cytnx::linalg::ExpM	(	const cytnx::UniTensor &	Tin,
		const T &	a,
		const T &	b = 0
	)

Perform the exponential function on a UniTensor.

This function performs the exponential function on a UniTensor Tin. For more details, please refer to the documentation of the function ExpM(const Tensor &Tin, const T &a, const T &b).

See also

ExpM(const Tensor &Tin, const T &a, const T &b)

ExpM() [3/4]

Tensor cytnx::linalg::ExpM

(

const Tensor &

in

)

perform matrix exponential for generic matrix

This function perform matrix exponential for generic matrix, That is,

\[ O = \exp{M} \]

Parameters

[in]

in

input Tensor, should be a square rank-2.

Returns

[Tensor]

ExpM() [4/4]

template<typename T >

Tensor cytnx::linalg::ExpM	(	const Tensor &	in,
		const T &	a,
		const T &	b = 0
	)

perform matrix exponential for generic matrix

This function perform matrix exponential for generic matrix, That is,

\[ O = \exp{aM + b} \]

Parameters

[in]	in	input Tensor, should be a square rank-2.
[in]	a	rescale factor
[in]	b	bias

Returns

[Tensor]

Gemm()

Tensor cytnx::linalg::Gemm	(	const Scalar &	a,
		const Tensor &	x,
		const Tensor &	y
	)

Blas Gemm, performing \( a\textbf{x}\textbf{y} -> \) return.

This function performs

\[ return = a\textbf{x}\textbf{y}, \]

where \( \textbf{x},\textbf{y} \) are rank-2 Tensor and a is Scalar. The dtype of return Tensor will be the strongest among x, y and a.

Parameters

[in]	a	Scalar.
[in]	x	Tensor, rank-2 with shape (M,N)
[in]	y	Tensor, rank-2 with shape (N,K)

Returns

[Tensor] with shape (M,K)

Gemm_()

void cytnx::linalg::Gemm_	(	const Scalar &	a,
		const Tensor &	x,
		const Tensor &	y,
		const Scalar &	b,
		Tensor &	c
	)

Blas Gemm, performing \( \textbf{c} = a\textbf{x}\textbf{y} + b\textbf{c} \), inplacely.

This function performs

\[ \textbf{c} = a\textbf{x}\textbf{y} + b\textbf{c}, \]

where \( \textbf{x},\textbf{y},\textbf{c} \) are rank-2 Tensor and a, b are Scalars. The dtype of return Tensor will be the strongest among x, y and a b c.

Parameters

[in]	a	Scalar.
[in]	x	Tensor, rank-2 with shape (M,N)
[in]	y	Tensor, rank-2 with shape (N,K)
[in]	b	Scalar.
[in,out]	c	Tensor, rank-2 with shape (M,K), must be properly initialized with the correct shape.

Ger()

Tensor cytnx::linalg::Ger	(	const Tensor &	x,
		const Tensor &	y,
		const Scalar &	a = Scalar()
	)

Blas Ger, performing return = a*vec(x)*vec(y)^T.

This function performs a*x*y^T where x,y are rank-1 Tensor with dimension nx and ny respectively; and a is a Scalar. The dtype of return Tensor will be the strongest among x,y and a.

Parameters

[in]	x	Tensor, rank-1 with size nx
[in]	y	Tensor, rank-1 with size ny
[in]	a	Scalar, if not provided a = 1.

Returns

[Tensor with shape (nx,ny)]

Note

This will return a new tensor.

Gesvd() [1/2]

std::vector< cytnx::UniTensor > cytnx::linalg::Gesvd	(	const cytnx::UniTensor &	Tin,
		const bool &	is_U = true,
		const bool &	is_vT = true
	)

Perform Singular-Value decomposition on a UniTensor using ?gesvd method.

This function performs the Singular-Value decomposition on a UniTensor Tin. The result will depend on the rowrank of the UniTensor Tin. For more details, please refer to the documentation of the function Gesvd(const Tensor &Tin, const bool &is_U, const bool &is_vT).

Gesvd() [2/2]

std::vector< Tensor > cytnx::linalg::Gesvd	(	const Tensor &	Tin,
		const bool &	is_U = true,
		const bool &	is_vT = true
	)

Perform Singular-Value decomposition on a rank-2 Tensor (a matrix).

This function will perform Singular-Value decomposition on a matrix (a rank-2 Tensor). That means givent a matrix Tin as \( M \), then the result will be:

\[ M = U S V^\dagger, \]

where \( U \) is a left uniform matrix, \( S \) is a diagonal matrix with singular values, and \( V^\dagger \) is the conjugate transpose of the right uniform matrix \( V \). Furthermore, \( U \) and \( V \) are unitary matrices, and \( S \) is a non-negative diagonal matrix.

Parameters

[in]	Tin	a Tensor, it should be a rank-2 tensor (matrix)
[in]	is_U	whether need to return left unitary matrix.
[in]	is_vT	whether need to return right unitary matrix

Returns

[std::vector<Tensors>]

1. The first tensor is a 1-d tensor contanin the singular values
2. If is_U is true, then the tensor \( U \) will be pushed back to the vector, and if is_vT is true, \( V^\dagger \) will be pushed back to the vector.

Precondition

The input tensor should be a rank-2 tensor (matrix).

See also

Gesvd_truncate

Gesvd_truncate() [1/2]

std::vector< cytnx::UniTensor > cytnx::linalg::Gesvd_truncate	(	const cytnx::UniTensor &	Tin,
		const cytnx_uint64 &	keepdim,
		const double &	err = 0,
		const bool &	is_U = true,
		const bool &	is_vT = true,
		const bool &	return_err = false
	)

Perform Singular-Value decomposition on a UniTensor with truncation.

This function performs the Singular-Value decomposition on a UniTensor Tin and do the truncation on the singular values. The result will depend on the rowrank of the UniTensor Tin. For more details, please refer to the documentation of the function Gesvd_truncate(const Tensor &Tin, const cytnx_uint64 &keepdim, const double &err, const bool &is_U, const bool &is_vT, const bool &return_err).

See also

Gesvd_truncate(const Tensor &Tin, const cytnx_uint64 &keepdim, const double &err, const bool &is_U, const bool &is_vT, const bool &return_err)

Gesvd_truncate() [2/2]

std::vector< Tensor > cytnx::linalg::Gesvd_truncate	(	const Tensor &	Tin,
		const cytnx_uint64 &	keepdim,
		const double &	err = 0,
		const bool &	is_U = true,
		const bool &	is_vT = true,
		const bool &	return_err = false
	)

Perform the truncate Singular-Value decomposition on a rank-2 Tensor (a matrix).

This function will perform the truncate Singular-Value decomposition on a matrix (a rank-2 Tensor). It will perform the SVD first, and then truncate the singular values to the given cutoff err. That means givent a matrix Tin as \( M \), then the result will be:

\[ M = U S V^\dagger, \]

where \( S \) is a singular values matrix with the singular values truncated to the given cutoff err. The dimension of \( S \) is at most keepdim.

Parameters

[in]	Tin	a Tensor, it should be a rank-2 tensor (matrix)
[in]	keepdim	the number (at most) of singular values to keep.
[in]	err	the cutoff error (the singular values smaller than err will be truncated.)
[in]	is_U	whether need to return a left unitary matrix.
[in]	is_vT	whether need to return a right unitary matrix.
[in]	return_err	whether need to return the error. If return_err is true, then the error will be pushed back to the vector. It is the smallest singular value in the singular values matrix \( S \).

Returns

[std::vector<Tensors>]

1. The first tensor is a 1-d tensor contanin the singular values
2. If is_U is true, then the tensor \( U\) will be pushed back to the vector.
3. If is_U is true, then the tensor \( V^\dagger \) will be pushed back to the vector.
4. If return_err is true, then the error will be pushed back to the vector.

Precondition

The input tensor should be a rank-2 tensor (matrix).

See also

Svd

Hosvd() [1/2]

std::vector< cytnx::UniTensor > cytnx::linalg::Hosvd	(	const cytnx::UniTensor &	Tin,
		const std::vector< cytnx_uint64 > &	mode,
		const bool &	is_core = true,
		const bool &	is_Ls = false,
		const std::vector< cytnx_int64 > &	trucate_dim = std::vector< cytnx_int64 >()
	)

Hosvd() [2/2]

std::vector< Tensor > cytnx::linalg::Hosvd	(	const Tensor &	Tin,
		const std::vector< cytnx_uint64 > &	mode,
		const bool &	is_core = true,
		const bool &	is_Ls = false,
		const std::vector< cytnx_int64 > &	trucate_dim = std::vector< cytnx_int64 >()
	)

iAdd()

void cytnx::linalg::iAdd	(	Tensor &	Lt,
		const Tensor &	Rt
	)

The addition function for Tensor, inplacely.

This is the inplace addtion function between two Tensor. It will perform the element-wise addtion. That means if the left Tensor Lt is given as \( T_L \) and the right Tensor Rt is given as \( T_R \), then the result will be:

\[ T_L[i] = T_L[i] + T_R[i], \]

where \( T_L[i] \) and \( T_R[i] \) are the elements in the Tensor \( T_L \) and \( T_R \). It will perform the element-wise addtion and note that it will modify the left Tensor Lt.

Parameters

[in,out]	Lt	The left Tensor.
[in]	Rt	The right Tensor.

Precondition

The shape of Lt and Rt must be the same.

Note

Compare to the function Add(const Tensor &Lt, const Tensor &Rt), this is a inplace function and it will modify the left Tensor Lt.

See also

Add(const Tensor &Lt, const Tensor &Rt), Add(const T &lc, const Tensor &Rt), Add(const Tensor &Lt, const T &rc), operator+(const Tensor &Lt, const Tensor &Rt)

iDiv()

void cytnx::linalg::iDiv	(	Tensor &	Lt,
		const Tensor &	Rt
	)

The inplace division function for Tensor, inplacely.

This is the inplace division function between two Tensor. It will perform the element-wise division. That means if the left Tensor Lt is given as \( T_L \) and the right Tensor Rt is given as \( T_R \), then the result will be:

\[ T_o[i] = T_L[i] / T_R[i] \]

where \( T_L[i] \) and \( T_R[i] \) are the elements in the Tensor \( T_L \) and \( T_R \). It will perform the element-wise division and note that it will modify the left Tensor Lt.

Parameters

[in,out]	Lt	The left Tensor.
[in]	Rt	The right Tensor.

Precondition

the right Tensor Rt should not contain any zero element.

Note

compare to the Div(const Tensor &Lt, const Tensor &Rt) function, this is a inplace function, which will modify the left Tensor Lt.

See also

Div(const Tensor &Lt, const Tensor &Rt), Div(const T &lc, const Tensor &Rt), Div(const Tensor &Lt, const T &rc), operator/(const Tensor &Lt, const Tensor &Rt)

iMul()

void cytnx::linalg::iMul	(	Tensor &	Lt,
		const Tensor &	Rt
	)

The multiplication function for Tensor, inplacely.

This is the multiplication function between two Tensor. It will perform the element-wise multiplication. That means if the left Tensor Lt is given as \( T_L \) and the right Tensor Rt is given as \( T_R \), then the result will be:

\[ T_o[i] = T_L[i] * T_R[i] \]

where \( T_L[i] \) and \( T_R[i] \) are the elements in the Tensor \( T_L \) and \( T_R \). It will perform the element-wise multiplication and note that it will modify the left Tensor Lt.

Parameters

[in,out]	Lt	The left Tensor.
[in]	Rt	The right Tensor.

Note

Compare to Mul(const Tensor &Lt, const Tensor &Rt), this is inplace function and will modify the left Tensor Lt.

See also

Mul(const Tensor &Lt, const Tensor &Rt), Mul(const T &lc, const Tensor &Rt), Mul(const Tensor &Lt, const T &rc), operator*(const Tensor &Lt, const Tensor &Rt)

Inv()

Tensor cytnx::linalg::Inv	(	const Tensor &	Tin,
		const double &	clip
	)

Element-wise inverse with clip.

This function will perform Element-wise inverse with clip. If A[i] < clip, then 1/A[i] = 0 will be set. That is, the out put will be:

\[ A_{out} = \left\{ \begin{array}{ll} 1/A[i] & \mathrm{if} \ A[i] \geq \mathrm{clip} \\ 0 & \mathrm{otherwise} \end{array} \right. \]

Parameters

[in]	Tin	a Tensor
[in]	clip	the clip value.

Returns

[Tensor]

Note

For complex type Tensors, the square norm is used to determine the clip.

Inv_()

void cytnx::linalg::Inv_	(	Tensor &	Tin,
		const double &	clip
	)

inplace perform Element-wise inverse with clip.

This function will perform Element-wise inverse with clip. This function is just as same as Inv, but it will modify the input Tensor inplace.

Parameters

[in]	Tin	a Tensor
[in]	clip	the clip value.

Returns

[Tensor]

Note

1. For complex type Tensors, the square norm is used to determine the clip.
2. on return, all the elements will be modified to it's inverse. if Tin is integer type, it will automatically promote to Type.Double.

InvM()

Tensor cytnx::linalg::InvM

(

const Tensor &

Tin

)

Matrix inverse.

This function will perform matrix inverse on the input matrix Tin.

Returns

[Tensor] the inversion of the input matrix.

Precondition

Tin should be a rank-2 Tensor.

InvM_()

void cytnx::linalg::InvM_

(

Tensor &

Tin

)

inplace matrix inverse.

This function will perform matrix inverse on the input matrix Tin, inplacely.

Note

Compare to InvM, this is inlpace function. The input matrix will be modified to it's inverse.

Precondition

the Tin should be a rank-2 Tensor.

iSub()

void cytnx::linalg::iSub	(	Tensor &	Lt,
		const Tensor &	Rt
	)

The subtraction function for Tensot, inplscely.

This is the subtraction function between two Tensor. It will perform the element-wise subtraction. That means if the left Tensor Lt is given as \( T_L \) and the right Tensor Rt is given as \( T_R \), then the result will be:

\[ T_L[i] = T_L[i] - T_R[i], \]

where \( T_L[i] \) and \( T_R[i] \) are the elements in the Tensor \( T_L \) and \( T_R \). It will perform the element-wise subtraction and note that it will modify the left Tensor Lt.

Parameters

[in,out]	Lt	The left Tensor.
[in]	Rt	The right Tensor.

Precondition

The shape of Lt and Rt must be the same.

Note

Compare to the function Sub(const Tensor &Lt, const Tensor &Rt), this is a inplace function and it will modify the left Tensor Lt.

See also

Sub(const Tensor &Lt, const Tensor &Rt), Sub(const T &lc, const Tensor &Rt), Sub(const Tensor &Lt, const T &rc), operator-(const Tensor &Lt, const Tensor &Rt)

Kron()

Tensor cytnx::linalg::Kron	(	const Tensor &	Tl,
		const Tensor &	Tr,
		const bool &	Tl_pad_left = false,
		const bool &	Tr_pad_left = false
	)

perform kronecker produces of two Tensor.

This function will perform kronecker produces of two Tensor Tl and Tr. Furthermore, the function assume two tensor has the same rank. In case where two tensors have different ranks, the small one will be extend by adding redundant dimension to the beginning of axis (T<x>_pad_right=true) or by adding redundant dim to the last axis (if T<x>_pad_left=false [default]). if the Tensor #1 has shape=(i1,j1,k1,l1...), and Tensor #2 has shape=(i2,j2,k2,l2...); then the return Tensor will have shape=(i1*i2,j1*j2,k1*k2...)

Parameters

[in]	Tl	rank-n Tensor #1
[in]	Tr	rank-m Tensor #2
[in]	Tl_pad_left	The padding scheme for Tl if Tl.rank != Tr.rank
[in]	Tr_pad_left	The padding scheme for Tr if Tl.rank != Tr.rank

Returns

[Tensor]

Precondition

two tensor should on same device.

Lanczos() [1/2]

std::vector< Tensor > cytnx::linalg::Lanczos	(	LinOp *	Hop,
		const Tensor &	Tin = Tensor(),
		const std::string	method = "Gnd",
		const double &	CvgCrit = 1.0e-14,
		const unsigned int &	Maxiter = 10000,
		const cytnx_uint64 &	k = 1,
		const bool &	is_V = true,
		const bool &	is_row = false,
		const cytnx_uint32 &	max_krydim = 0,
		const bool &	verbose = false
	)

perform Lanczos for hermitian/symmetric matrices or linear function.

This function calculate the eigen value problem using explicitly restarted Lanczos. #Performance tune: For small linear dimension, try to reduce max_krydim.

Parameters

[in]	Hop	the Linear Operator defined by LinOp class or it's inheritance (see LinOp).
[in]	Tin	the initial vector, this should be rank-1.
[in]	method	the desired Lanczos method to use, the supported options are: 'ER' : explicitly restarted Lanczos 'Gnd' : naive Lanczos

Parameters

[in]	CvgCrit	the convergence criterion of the energy.
[in]	maxiter	the maximum interation steps for each k.
[in]	k	the number of lowest k eigen values.
[in]	is_V	if set to true, the eigen vectors will be returned.
[in]	is_row	whether the return eigen vectors should be in row-major form.
[in]	max_krydim	the maximum krylov subspace dimension for each iteration.
[in]	verbose	print out iteration info.

Returns

[eigvals (Tensor), eigvecs (Tensor)(option)]

Note

To use, define a linear operator with LinOp class either by assign a custom function or create a class that inherit LinOp (see LinOp for further details)

Lanczos() [2/2]

std::vector< UniTensor > cytnx::linalg::Lanczos	(	LinOp *	Hop,
		const UniTensor &	Tin = UniTensor(),
		const std::string	method = "Gnd",
		const double &	CvgCrit = 1.0e-14,
		const unsigned int &	Maxiter = 10000,
		const cytnx_uint64 &	k = 1,
		const bool &	is_V = true,
		const bool &	is_row = false,
		const cytnx_uint32 &	max_krydim = 4,
		const bool &	verbose = false
	)

perform Lanczos for hermitian/symmetric matrices or linear function.

This function calculate the eigen value problem using explicitly restarted Lanczos. #Performance tune: For small linear dimension, try to reduce max_krydim.

Parameters

[in]	Hop	the Linear Operator defined by LinOp class or it's inheritance (see LinOp).
[in]	Tin	the initial vector, this should be rank-1.
[in]	method	the desired Lanczos method to use, the supported options are: 'ER' : explicitly restarted Lanczos 'Gnd' : naive Lanczos

Parameters

[in]	CvgCrit	the convergence criterion of the energy.
[in]	maxiter	the maximum interation steps for each k.
[in]	k	the number of lowest k eigen values.
[in]	is_V	if set to true, the eigen vectors will be returned.
[in]	is_row	whether the return eigen vectors should be in row-major form.
[in]	max_krydim	the maximum krylov subspace dimension for each iteration.
[in]	verbose	print out iteration info.

Returns

[eigvals (UniTensor), eigvecs (UniTensor)(option)]

Note

To use, define a linear operator with LinOp class either by assign a custom function or create a class that inherit LinOp (see LinOp for further details)

Lanczos_ER()

std::vector< Tensor > cytnx::linalg::Lanczos_ER	(	LinOp *	Hop,
		const cytnx_uint64 &	k = 1,
		const bool &	is_V = true,
		const cytnx_uint64 &	maxiter = 10000,
		const double &	CvgCrit = 1.0e-14,
		const bool &	is_row = false,
		const Tensor &	Tin = Tensor(),
		const cytnx_uint32 &	max_krydim = 4,
		const bool &	verbose = false
	)

perform Lanczos for hermitian/symmetric matrices or linear function.

This function calculate the eigen value problem using explicitly restarted Lanczos. #Performance tune: For small linear dimension, try to reduce max_krydim.

Parameters

[in]	Hop	the Linear Operator defined by LinOp class or it's inheritance (see LinOp).
[in]	k	the number of lowest k eigen values.
[in]	is_V	if set to true, the eigen vectors will be returned.
[in]	maxiter	the maximum interation steps for each k.
[in]	CvgCrit	the convergence criterion of the energy.
[in]	is_row	whether the return eigen vectors should be in row-major form.
[in]	Tin	the initial vector, this should be rank-1
[in]	max_krydim	the maximum krylov subspace dimension for each iteration.
[in]	verbose	print out iteration info.

Returns

[eigvals (Tensor), eigvecs (Tensor)(option)]

Note

To use, define a linear operator with LinOp class either by assign a custom function or create a class that inherit LinOp (see LinOp for further details)

Lanczos_Gnd()

std::vector< Tensor > cytnx::linalg::Lanczos_Gnd	(	LinOp *	Hop,
		const double &	CvgCrit = 1.0e-14,
		const bool &	is_V = true,
		const Tensor &	Tin = Tensor(),
		const bool &	verbose = false,
		const unsigned int &	Maxiter = 100000
	)

perform Lanczos for hermitian/symmetric matrices or linear function to get ground state and lowest eigen value

This function calculate the eigen value problem using naive Lanczos to get ground state and lowest eigen value.

Parameters

[in]	Hop	the Linear Operator defined by LinOp class or it's inheritance (see LinOp).
[in]	CvgCrit	the convergence criterion of the energy.
[in]	is_V	if set to true, the eigen vectors will be returned.
[in]	Tin	the initial vector, this should be rank-1
[in]	verbose	print out iteration info.
[in]	maxiter	the maximum interation steps for each k.

Returns

[eigvals (Tensor), eigvecs (Tensor)(option)]

Note

To use, define a linear operator with LinOp class either by assign a custom function or create a class that inherit LinOp (see LinOp for further details)

Lanczos_Gnd_Ut()

std::vector< UniTensor > cytnx::linalg::Lanczos_Gnd_Ut	(	LinOp *	Hop,
		const UniTensor &	Tin,
		const double &	CvgCrit = 1.0e-14,
		const bool &	is_V = true,
		const bool &	verbose = false,
		const unsigned int &	Maxiter = 100000
	)

perform Lanczos for hermitian/symmetric matrices or linear function to get ground state and lowest eigen value

This function calculate the eigen value problem using naive Lanczos to get ground state and lowest eigen value.

Parameters

[in]	Hop	the Linear Operator defined by LinOp class or it's inheritance (see LinOp).
[in]	CvgCrit	the convergence criterion of the energy.
[in]	is_V	if set to true, the eigen vectors will be returned.
[in]	Tin	the initial vector, this should be a UniTensor.
[in]	verbose	print out iteration info.
[in]	maxiter	the maximum interation steps for each k.

Returns

[eigvals (UniTensor::Dense), eigvecs (UniTensor)(option)]

Note

To use, define a linear operator with LinOp class either by assign a custom function or create a class that inherit LinOp (see LinOp for further details)

Lstsq()

std::vector< Tensor > cytnx::linalg::Lstsq	(	const Tensor &	A,
		const Tensor &	b,
		const float &	rcond = -1
	)

Return the least-squares solution to a linear matrix equation.

Computes the vector x that approximatively solves the equation A @ x = b. The equation may be under-, well-, or over-determined independent columns. If a is square and of full rank, then x (but for round-off error) is the “exact” solution of the equation. Else, x minimizes the Euclidean 2-norm \( || b - a x ||_2 \).

Parameters

[in]	A	“Coefficient” matrix, must be two-dimensional.
[in]	b	Ordinate or “dependent variable” values, must be two-dimensional, the least-squares solution is calculated for each of the K columns of b.
[in]	rcond	Cut-off ratio for small singular values of a. For the purposes of rank determination, singular values are treated as zero if they are smaller than rcond times the largest singular value of A, If it is negative, the machine precision is used.

Returns

[std::vector<Tensors>]

1. the first tensor is least-squares solutions in the K columns.
2. the second tensor is the sums of squared residuals: Squared Euclidean 2-norm for each column in b - a @ x. If the rank of a is < N or M <= N, this is a zero Tensor.
3. the third tensor is the rank of matrix A.
4. the forth tensor is singular values of A.

Author

Ke

Matmul()

Tensor cytnx::linalg::Matmul	(	const Tensor &	TL,
		const Tensor &	TR
	)

perform matrix multiplication on two tensors.

This function will perform matrix multiplication on two matrices (2-rank Tensor) TL and TR. The result will be:

\[ T = T_L T_R \]

Parameters

[in]	TL	a left Tensor
[in]	TR	a right Tensor

Precondition

the TL and TR should be rank-2 Tensor.

Matmul_dg()

Tensor cytnx::linalg::Matmul_dg	(	const Tensor &	Tl,
		const Tensor &	Tr
	)

perform matrix multiplication on two Tensors with one rank-1 and the other rank-2 where the rank-1 represent the diagonal elements of the specific tensor.

Note

one of TL and TR should be rank-1 Tensor and the other should be rank-2 Tensor.

Max()

Tensor cytnx::linalg::Max

(

const Tensor &

Tn

)

get the maximum element.

Parameters

[in]

Tn

a cytnx::Tensor

Note

For complex TN, only real part is compared.

Min()

Tensor cytnx::linalg::Min

(

const Tensor &

Tn

)

get the minimum element.

Parameters

[in]

Tn

a cytnx::Tensor

Note

For complex TN, only real part is compared.

Mod() [1/6]

cytnx::UniTensor cytnx::linalg::Mod	(	const cytnx::UniTensor &	Lt,
		const cytnx::UniTensor &	Rt
	)

element-wise modulo

The modulo function between two UniTensor.

This is the modulo function for UniTensor. It will perform the element-wise modulo between two UniTensor. That means if the UniTensor Lt is given as \( T_L \) and the UniTensor Rt is given as \( T_R \), then the result will be:

\[ T_o[i] = T_L[i] \mod T_R[i], \]

where \( T_L[i] \) and \( T_R[i] \) are the elements in the UniTensor \( T_L \) and \( T_R \).

Parameters

[in]	Lt	The left UniTensor.
[in]	Rt	The right UniTensor.

Returns

The result UniTensor.

Precondition

1. Lt and Rt must have the same shape.
2. The input UniTensor Lt and Rt need to be integer type.

See also

UniTensor::Mod(const UniTensor &Rt) const, operator%(const UniTensor &Lt, const UniTensor &Rt)

Mod() [2/6]

template<class T >

cytnx::UniTensor cytnx::linalg::Mod	(	const cytnx::UniTensor &	Lt,
		const T &	rc
	)

The modulo function between a UniTensor and a template type.

This is the modulo function for UniTensor. It will perform the element-wise modulo between a UniTensor and a template type. That means if the UniTensor Lt is given as \( T_i \) and the template type rc is given as \( c \), then the result will be:

\[ T_o[i] = T_i[i] \mod c, \]

where \( T_i[i] \) and \( T_o[i] \) are the elements in the UniTensor \( T_i \) and \( T_o \).

Parameters

[in]	Lt	The left UniTensor.
[in]	rc	The right template type. supported type: Scalar, cytnx::cytnx_int64, cytnx::cytnx_uint64, cytnx::cytnx_int32, cytnx::cytnx_uint32, cytnx::cytnx_int16, cytnx::cytnx_uint16, cytnx::cytnx_bool.

Returns

The result UniTensor.

Precondition

The input Lt and rc need to be integer type.

Note

The inpute template type rc will be casted to the same type as the UniTensor Lt.

See also

operator%(const UniTensor &Lt, const T &rc), Mod(const cytnx::UniTensor &Lt, const T &rc)

Mod() [3/6]

template<class T >

cytnx::UniTensor cytnx::linalg::Mod	(	const T &	lc,
		const cytnx::UniTensor &	Rt
	)

The modulo function between a UniTensor and a template type.

This is the modulo function for UniTensor. It will perform the element-wise modulo between a UniTensor and a template type. That means if the template type lc is given as \( c \) and the UniTensor Rt is given as \( T_i \), then the result will be:

\[ T_o[i] = c \mod T_i[i], \]

where \( T_i[i] \) and \( T_o[i] \) are the elements in the UniTensor \( T_i \) and \( T_o \).

Parameters

lc	The left template type. The right template type. supported type: Scalar, cytnx::cytnx_int64, cytnx::cytnx_uint64, cytnx::cytnx_int32, cytnx::cytnx_uint32, cytnx::cytnx_int16, cytnx::cytnx_uint16, cytnx::cytnx_bool.
Rt	The right UniTensor.

Returns

The result UniTensor.

Precondition

The input lc and Rt need to be integer type.

Note

The inpute template type lc will be casted to the same type as the UniTensor Rt.

See also

operator%(const UniTensor &Lt, const T &rc), Mod(const cytnx::UniTensor &Lt, const T &rc)

Mod() [4/6]

template<class T >

Tensor cytnx::linalg::Mod	(	const T &	lc,
		const Tensor &	Rt
	)

The mod function for Tensor.

This is the mod function between a Tensor and a template type. It will perform the element-wise mod. That means if the left template type lc is given as \( c \) and the right Tensor Rt is given as \( T_R \), then the result will be:

\[ T_o[i] = c % T_R[i] \]

where \( T_R[i] \) is the elements in the Tensor \( T_R \). It will perform the element-wise mod and note that it will return a new Tensor object.

Parameters

[in]	lc	The left template type.
[in]	Rt	The right Tensor.

Returns

The result Tensor.

Precondition

the right template type rc should be integer type.

See also

Mod(const Tensor &Lt, const Tensor &Rt), Mod(const Tensor &Lt, const T &rc)

Mod() [5/6]

template<class T >

Tensor cytnx::linalg::Mod	(	const Tensor &	Lt,
		const T &	rc
	)

The mod function for Tensor.

This is the mod function between a Tensor and a template type. It will perform the element-wise mod. That means if the left Tensor Lt is given as \( T_L \) and the right template type rc is given as \( c \), then the result will be:

\[ T_o[i] = T_L[i] % c \]

where \( T_L[i] \) is the elements in the Tensor \( T_L \). It will perform the element-wise mod and note that it will return a new Tensor object.

Parameters

[in]	Lt	The left Tensor.
[in]	rc	The right template type.

Returns

The result Tensor.

Precondition

the right template type rc should be integer type.

See also

Mod(const Tensor &Lt, const Tensor &Rt), Mod(const T &lc, const Tensor &Rt)

Mod() [6/6]

Tensor cytnx::linalg::Mod	(	const Tensor &	Lt,
		const Tensor &	Rt
	)

The mod function for Tensor.

This is the mod function between two Tensor. It will perform the element-wise mod. That means if the left Tensor Lt is given as \( T_L \) and the right Tensor Rt is given as \( T_R \), then the result will be:

\[ T_o[i] = T_L[i] % T_R[i] \]

where \( T_L[i] \) and \( T_R[i] \) are the elements in the Tensor \( T_L \) and \( T_R \). It will perform the element-wise mod and note that it will return a new Tensor object.

Parameters

[in]	Lt	The left Tensor.
[in]	Rt	The right Tensor.

Returns

The result Tensor.

Precondition

The input tensors Lt and Rt should have the same shape and need to be integer type.

See also

Mod(const T &lc, const Tensor &Rt), Mod(const Tensor &Lt, const T &rc),

Mul() [1/6]

cytnx::UniTensor cytnx::linalg::Mul	(	const cytnx::UniTensor &	Lt,
		const cytnx::UniTensor &	Rt
	)

The multiplication function between two UniTensor.

This is the multiplication function for UniTensor. It will multiply the two UniTensor together. It will multiply every element in the UniTensor Lt with the corresponding element in the UniTensor Rt. That means if the UniTensor Lt is given as \( T_L \) and the UniTensor Rt is given as \( T_R \), then the result will be:

\[ T_o[i] = T_L[i] \times T_R[i], \]

where \( T_L[i] \) and \( T_R[i] \) are the elements in the UniTensor \( T_L \) and \( T_R \). It will perform the element-wise multiplication and note that it will return a new UniTensor object.

Parameters

[in]	Lt	The left UniTensor.
[in]	Rt	The right UniTensor.

Returns

The result UniTensor.

Precondition

Lt and Rt must have the same shape.

See also

UniTensor::Mul(const UniTensor &Rt) const, operator*(const UniTensor &Lt, const UniTensor &Rt)

Mul() [2/6]

template<class T >

cytnx::UniTensor cytnx::linalg::Mul	(	const cytnx::UniTensor &	Lt,
		const T &	rc
	)

The multiplication function between a UniTensor and a template type.

This is the multiplication function for UniTensor. It will multiply the UniTensor and a template type together. It will multiply every element in the UniTensor with the template type. That means if the UniTensor Lt is given as \( T_i \) and the template type rc is given as \( c \), then the result will be:

\[ T_o[i] = T_i[i] \times c, \]

where \( T_i[i] \) and \( T_o[i] \) are the elements in the UniTensor \( T_i \) and \( T_o \).

Parameters

[in]	Lt	The left UniTensor.
[in]	rc	The right template type. supported type: Scalar, cytnx::cytnx_complex128, cytnx::cytnx_complex64, cytnx::cytnx_double, cytnx::cytnx_float, cytnx::cytnx_int64, cytnx::cytnx_uint64, cytnx::cytnx_int32, cytnx::cytnx_uint32, cytnx::cytnx_int16, cytnx::cytnx_uint16, cytnx::cytnx_bool.

Returns

The result UniTensor.

Precondition

The supported template type shown above.

Note

The inpute template type rc will be casted to the same type as the UniTensor Lt.

See also

operator*(const UniTensor &Lt, const T &rc), Mul(const cytnx::UniTensor &Lt, const T &rc)

Mul() [3/6]

template<class T >

cytnx::UniTensor cytnx::linalg::Mul	(	const T &	lc,
		const cytnx::UniTensor &	Rt
	)

The multiplication function between a UniTensor and a template type.

This is the multiplication function for UniTensor. It will multiply the UniTensor and a template type together. It will multiply every element in the UniTensor with the template type. That means if the template type lc is given as \( c \) and the UniTensor Rt is given as \( T_i \), then the result will be:

\[ T_o[i] = c \times T_i[i], \]

where \( T_i[i] \) and \( T_o[i] \) are the elements in the UniTensor \( T_i \) and \( T_o \).

Parameters

[in]	Lt	The left UniTensor.
[in]	rc	The right template type. supported type: Scalar, cytnx::cytnx_complex128, cytnx::cytnx_complex64, cytnx::cytnx_double, cytnx::cytnx_float, cytnx::cytnx_int64, cytnx::cytnx_uint64, cytnx::cytnx_int32, cytnx::cytnx_uint32, cytnx::cytnx_int16, cytnx::cytnx_uint16, cytnx::cytnx_bool.

Returns

The result UniTensor.

Precondition

The supported template type shown above.

Note

The inpute template type lc will be casted to the same type as the UniTensor Rt.

See also

operator*(const T &lc, const UniTensor &Rt), Mul(const T &lc, const cytnx::UniTensor &Rt)

Mul() [4/6]

template<class T >

Tensor cytnx::linalg::Mul	(	const T &	lc,
		const Tensor &	Rt
	)

The multiplication function for Tensor.

This is the multiplication function between a Tensor and a template type. It will perform the element-wise multiplication. That means if the left Tensor Lt is given as \( T_L \) and the template type rc is given as \( c \), then the result will be:

\[ T_o[i] = T_L[i] * c, \]

where \( T_L[i] \) is the elements in the Tensor \( T_L \). It will perform the element-wise multiplication and note that it will return a new Tensor object.

Parameters

[in]	Lt	The left Tensor.
[in]	rc	The right template type.

Returns

The result Tensor.

See also

Mul(const Tensor &Lt, const Tensor &Rt), Mul(const T &lc, const Tensor &Rt), iMul(Tensor &Lt, const Tensor &Rt), operator*(const Tensor &Lt, const Tensor &Rt)

Mul() [5/6]

template<class T >

Tensor cytnx::linalg::Mul	(	const Tensor &	Lt,
		const T &	rc
	)

The multiplication function for Tensor.

This is the multiplication function between a Tensor and a template type. It will perform the element-wise multiplication. That means if the left Tensor Lt is given as \( T_L \) and the template type rc is given as \( c \), then the result will be:

\[ T_o[i] = T_L[i] * c, \]

where \( T_L[i] \) is the elements in the Tensor \( T_L \). It will perform the element-wise multiplication and note that it will return a new Tensor object.

Parameters

[in]	Lt	The left Tensor.
[in]	rc	The right template type.

Returns

The result Tensor.

See also

Mul(const Tensor &Lt, const Tensor &Rt), Mul(const T &lc, const Tensor &Rt), iMul(Tensor &Lt, const Tensor &Rt), operator*(const Tensor &Lt, const Tensor &Rt)

Mul() [6/6]

Tensor cytnx::linalg::Mul	(	const Tensor &	Lt,
		const Tensor &	Rt
	)

The multiplication function for Tensor.

This is the multiplication function between two Tensor. It will perform the element-wise multiplication. That means if the left Tensor Lt is given as \( T_L \) and the right Tensor Rt is given as \( T_R \), then the result will be:

\[ T_o[i] = T_L[i] * T_R[i] \]

where \( T_L[i] \) and \( T_R[i] \) are the elements in the Tensor \( T_L \) and \( T_R \). It will perform the element-wise multiplication and note that it will return a new Tensor object.

Parameters

[in]	Lt	The left Tensor.
[in]	Rt	The right Tensor.

Returns

The result Tensor.

See also

Mul(const T &lc, const Tensor &Rt), Mul(const Tensor &Lt, const T &rc), iMul(Tensor &Lt, const Tensor &Rt), operator*(const Tensor &Lt, const Tensor &Rt)

Norm()

Tensor cytnx::linalg::Norm

(

const Tensor &

Tl

)

Calculate the norm of a tensor.

This function will calculate the norm of a tensor. If the input tensor is rank-1, then the frobenius norm will be calculated. If the input tensor is rank-N with N>=2, then the tensor will be flatten (see flatten()) to 1d first, and then calculate the frobenius norm.

Parameters

[in]

Tl

input Tensor

Returns

Tensor

Outer()

Tensor cytnx::linalg::Outer	(	const Tensor &	Tl,
		const Tensor &	Tr
	)

perform outer produces of two rank-1 Tensor.

This function will perform outer produces of two rank-1 Tensor Tl and Tr. Furthermore, if the Tensor Tl has [shape_1], and Tensor Tr has [shape_2]; then the return Tensor will have shape: concate(shape_1,shape_2)

Parameters

[in]	Tl	rank-1 Tensor #1
[in]	Tr	rank-1 Tensor #2

Returns

[Tensor]

Precondition

two tensor should on same device.

Pow() [1/2]

Tensor cytnx::linalg::Pow	(	const Tensor &	Tin,
		const double &	p
	)

take power p on all the elements in Tensor.

This function will perform power p on all the elements in Tensor Tin. That is, the output will be:

\[ T_{o}[i] = T_{i}[i]^{p} \]

Parameters

[in]

p,the

power

Returns

[Tensor]

Pow() [2/2]

UniTensor cytnx::linalg::Pow	(	const UniTensor &	Tin,
		const double &	p
	)

take power p on all the elements in UniTensor.

This function will take power p on all the elements in UniTensor.

Parameters

[in]	Tin	the input UniTensor
[in]	p	the power

Precondition

If Tin is a real UniTensor and containt negative elements, then p must be an integer.

Returns

UniTensor with the same shape as Tin, but with the elements are the power of Tin.

Note

Compare to the Pow_(UniTensor &Tin, const double &p) function, this function will not modify the input UniTensor and return a new UniTensor.

See also

Pow_(UniTensor &Tin, const double &p)

Pow_() [1/2]

void cytnx::linalg::Pow_	(	Tensor &	Tin,
		const double &	p
	)

inplace perform power on all the elements in Tensor.

this is just a inplace version of Pow. The input Tensor Tin will be modified.

Parameters

[in]	Tin,the	input Tensor.
[in]	p,the	power.

Pow_() [2/2]

void cytnx::linalg::Pow_	(	UniTensor &	Tin,
		const double &	p
	)

Take power p on all the elements in UniTensor, inplacely.

This function will take power p on all the elements in UniTensor, inplacely.

Parameters

[in,out]	Tin	the input UniTensor
[in]	p	the power

Precondition

If Tin is a real UniTensor and containt negative elements, then p must be an integer.

Note

Compare to the Pow function, this is an inplacely function, which will modify the input UniTensor.

See also

Pow(const UniTensor &Tin, const double &p)

Qdr() [1/2]

std::vector< cytnx::UniTensor > cytnx::linalg::Qdr	(	const cytnx::UniTensor &	Tin,
		const bool &	is_tau = false
	)

Perform the QDR decomposition on a UniTensor.

This function performs the QDR decomposition on a UniTensor Tin. The result will depend on the rowrank of the UniTensor Tin. For more details, please refer to the documentation of the function Qdr(const Tensor &Tin, const bool &is_tau).

See also

Qdr(const Tensor &Tin, const bool &is_tau)

Qdr() [2/2]

std::vector< Tensor > cytnx::linalg::Qdr	(	const Tensor &	Tin,
		const bool &	is_tau = false
	)

Perform QDR decomposition on a rank-2 Tensor.

Parameters

[in]	Tin	a cytnx::Tensor, it should be a rank-2 tensor (matrix)
[in]	is_tau	if return the tau that contains the Householder reflectors that generate q along with r. The tau array contains scaling factors for the reflectors

Returns

[std::vector<Tensors>]

1. the first tensor is the orthomormal matrix \( Q \), a 2-d tensor (matrix)
2. the second tensor is the diagonal matrix \( D \), a 1-d tensor (diagonal matrix)
3. the third tensor is the right-upper triangular matrix \( R \), a 2-d tensor (matrix)
4. the forth tensor is the Householder reflectors \( H \), a 1-d tensor (vector). This tensor will only return when is_tau = true.

Precondition

The input tensor should be a rank-2 tensor (matrix).

See also

Qr

Qr() [1/2]

std::vector< cytnx::UniTensor > cytnx::linalg::Qr	(	const cytnx::UniTensor &	Tin,
		const bool &	is_tau = false
	)

Perform the QR decomposition on a UniTensor.

This function performs the QR decomposition on a UniTensor Tin. The result will depend on the rowrank of the UniTensor Tin. For more details, please refer to the documentation of the function Qr(const Tensor &Tin, const bool &is_tau).

See also

Qr(const Tensor &Tin, const bool &is_tau)

Qr() [2/2]

std::vector< Tensor > cytnx::linalg::Qr	(	const Tensor &	Tin,
		const bool &	is_tau = false
	)

Perform QR decomposition on a rank-2 Tensor.

This function will perform QR decomposition on a matrix (a rank-2 Tensor). That means givent a matrix Tin as \( M \), then the result will be:

\[ M = Q R, \]

where \( Q \) is a orthogonal matrix, and \( R \) is a right-upper triangular matrix.

Parameters

[in]	Tin	a Tensor, it should be a rank-2 tensor (a matrix)
[in]	is_tau	if return the tau that contains the Householder reflectors that generate q along with r. The tau array contains scaling factors for the reflectors

Returns

[std::vector<Tensors>]

1. the first tensor is the orthomormal matrix \( Q \), a 2-d tensor (matrix)
2. the second tensor is the right-upper triangular matrix \( R \), a 2-d tensor (matrix)
3. the third tensor is the Householder reflectors \( H \), a 1-d tensor (vector). This tensor will only return when is_tau = true.

Precondition

The input tensor should be a rank-2 tensor (matrix).

See also

Qdr

Sub() [1/6]

cytnx::UniTensor cytnx::linalg::Sub	(	const cytnx::UniTensor &	Lt,
		const cytnx::UniTensor &	Rt
	)

The subtraction function between two UniTensor.

This is the subtraction function for UniTensor. It will subtract the UniTensor and a template type together. It will subtract every element in the UniTensor with the template type. That means if the UniTensor Lt is given as \( T_L \) and the UniTensor Rt is given as \( T_R \), then the result will be:

\[ T_o[i] = T_L[i] - T_R[i], \]

where \( T_L[i] \) and \( T_R[i] \) are the elements in the UniTensor \( T_L \) and \( T_R \). It will perform the element-wise subtraction and note that it will return a new UniTensor object.

Parameters

[in]	Lt	The left UniTensor.
[in]	Rt	The right UniTensor.

Returns

The result UniTensor.

Precondition

Lt and Rt must have the same shape.

See also

UniTensor::Sub(const UniTensor &Rt) const, operator-(const UniTensor &Lt, const UniTensor &Rt)

Sub() [2/6]

template<class T >

cytnx::UniTensor cytnx::linalg::Sub	(	const cytnx::UniTensor &	Lt,
		const T &	rc
	)

The subtraction function between a UniTensor and a template type.

This is the subtraction function for UniTensor. It will subtract the UniTensor and a template type together. It will subtract every element in the UniTensor with the template type. That means if the UniTensor Lt is given as \( T_i \) and the template type rc is given as \( c \), then the result will be:

\[ T_o[i] = T_i[i] - c, \]

where \( T_i[i] \) and \( T_o[i] \) are the elements in the UniTensor \( T_i \) and \( T_o \).

Parameters

[in]	Lt	The left UniTensor.
[in]	rc	The right template type. supported type: Scalar, cytnx::cytnx_complex128, cytnx::cytnx_complex64, cytnx::cytnx_double, cytnx::cytnx_float, cytnx::cytnx_int64, cytnx::cytnx_uint64, cytnx::cytnx_int32, cytnx::cytnx_uint32, cytnx::cytnx_int16, cytnx::cytnx_uint16, cytnx::cytnx_bool.

Returns

The result UniTensor.

Precondition

The supported template type shown above.

Note

The inpute template type rc will be casted to the same type as the UniTensor Lt.

See also

operator-(const UniTensor &Lt, const T &rc), Sub(const cytnx::UniTensor &Lt, const T &rc)

Sub() [3/6]

template<class T >

cytnx::UniTensor cytnx::linalg::Sub	(	const T &	lc,
		const cytnx::UniTensor &	Rt
	)

The subtraction function between a UniTensor and a template type.

This is the subtraction function for UniTensor. It will subtract the UniTensor and a template type together. It will subtract every element in the UniTensor with the template type. That means if the template type lc is given as \( c \) and the UniTensor Rt is given as \( T_i \), then the result will be:

\[ T_o[i] = c - T_i[i], \]

where \( T_i[i] \) and \( T_o[i] \) are the elements in the UniTensor \( T_i \) and \( T_o \).

Parameters

[in]	Lt	The left UniTensor.
[in]	rc	The right template type. supported type: Scalar, cytnx::cytnx_complex128, cytnx::cytnx_complex64, cytnx::cytnx_double, cytnx::cytnx_float, cytnx::cytnx_int64, cytnx::cytnx_uint64, cytnx::cytnx_int32, cytnx::cytnx_uint32, cytnx::cytnx_int16, cytnx::cytnx_uint16, cytnx::cytnx_bool.

Returns

The result UniTensor.

Precondition

The supported template type shown above.

Note

The inpute template type lc will be casted to the same type as the UniTensor Rt.

See also

operator-(const T &lc, const UniTensor &Rt), Sub(const T &lc, const cytnx::UniTensor &Rt)

Sub() [4/6]

template<class T >

Tensor cytnx::linalg::Sub	(	const T &	lc,
		const Tensor &	Rt
	)

The subtraction function for Tensor.

This is the subtraction function between a Tensor and a template type. It will perform the element-wise subtraction. That means if the template type lc is given as \( c \) and the right Tensor Rt is given as \( T_R \), then the result will be:

\[ T_o[i] = c - T_R[i], \]

where \( T_R[i] \) is the elements in the Tensor \( T_R \). It will perform the element-wise subtraction and note that it will return a new Tensor object.

Parameters

[in]	lc	The left template type.
[in]	Rt	The right Tensor.

Returns

The result Tensor.

See also

Sub(const Tensor &Lt, const Tensor &Rt), Sub(const Tensor &Lt, const T &rc), iSub(Tensor &Lt, const Tensor &Rt), operator-(const Tensor &Lt, const Tensor &Rt)

Sub() [5/6]

template<class T >

Tensor cytnx::linalg::Sub	(	const Tensor &	Lt,
		const T &	rc
	)

The subtraction function for Tensor.

This is the subtraction function between a Tensor and a template type. It will perform the element-wise subtraction. That means if the left Tensor Lt is given as \( T_L \) and the template type rc is given as \( c \), then the result will be:

\[ T_o[i] = T_L[i] - c, \]

where \( T_L[i] \) is the elements in the Tensor \( T_L \). It will perform the element-wise subtraction and note that it will return a new Tensor object.

Parameters

[in]	Lt	The left Tensor.
[in]	rc	The right template type.

Returns

The result Tensor.

See also

Sub(const Tensor &Lt, const Tensor &Rt), Sub(const T &lc, const Tensor &Rt), iSub(Tensor &Lt, const Tensor &Rt), operator-(const Tensor &Lt, const Tensor &Rt)

Sub() [6/6]

Tensor cytnx::linalg::Sub	(	const Tensor &	Lt,
		const Tensor &	Rt
	)

The subtraction function for Tensor.

This is the subtraction function between two Tensor. It will perform the element-wise subtraction. That means if the left Tensor Lt is given as \( T_L \) and the right Tensor Rt is given as \( T_R \), then the result will be:

\[ T_o[i] = T_L[i] - T_R[i], \]

where \( T_L[i] \) and \( T_R[i] \) are the elements in the Tensor \( T_L \) and \( T_R \). It will perform the element-wise subtraction and note that it will return a new Tensor object.

Parameters

[in]	Lt	The left Tensor.
[in]	Rt	The right Tensor.

Returns

The result Tensor.

See also

Sub(const T &lc, const Tensor &Rt), Sub(const Tensor &Lt, const T &rc), iSub(Tensor &Lt, const Tensor &Rt), operator-(const Tensor &Lt, const Tensor &Rt)

Sum()

Tensor cytnx::linalg::Sum

(

const Tensor &

Tn

)

get the sum of all the elements.

Parameters

[in]

Tn

a cytnx::Tensor

Svd() [1/2]

std::vector< cytnx::UniTensor > cytnx::linalg::Svd	(	const cytnx::UniTensor &	Tin,
		const bool &	is_UvT = true
	)

Perform Singular-Value decomposition on a UniTensor using divide-and-conquer method.

This function performs the Singular-Value decomposition on a UniTensor Tin. The result will depend on the rowrank of the UniTensor Tin. For more details, please refer to the documentation of the function Svd(const Tensor &Tin, const bool &is_UvT).

Svd() [2/2]

std::vector< Tensor > cytnx::linalg::Svd	(	const Tensor &	Tin,
		const bool &	is_UvT = true
	)

Perform Singular-Value decomposition on a rank-2 Tensor (a matrix).

This function will perform Singular-Value decomposition on a matrix (a rank-2 Tensor). That means givent a matrix Tin as \( M \), then the result will be:

\[ M = U S V^\dagger, \]

where \( U \) is a left uniform matrix, \( S \) is a diagonal matrix with singular values, and \( V^\dagger \) is the conjugate transpose of the right uniform matrix \( V \). Furthermore, \( U \) and \( V \) are unitary matrices, and \( S \) is a non-negative diagonal matrix.

Parameters

[in]	Tin	a Tensor, it should be a rank-2 tensor (matrix)
[in]	is_UvT	whether need to return a left unitary matrix.

Returns

[std::vector<Tensors>]

1. The first tensor is a 1-d tensor contanin the singular values
2. If is_UvT is true, then the tensors \( U,V^\dagger \) will be pushed back to the vector.

Precondition

The input tensor should be a rank-2 tensor (matrix).

See also

Svd_truncate

Svd_truncate() [1/2]

std::vector< cytnx::UniTensor > cytnx::linalg::Svd_truncate	(	const cytnx::UniTensor &	Tin,
		const cytnx_uint64 &	keepdim,
		const double &	err = 0,
		const bool &	is_UvT = true,
		const bool &	return_err = false
	)

Perform Singular-Value decomposition on a UniTensor with truncation.

This function performs the Singular-Value decomposition on a UniTensor Tin and do the truncation on the singular values. The result will depend on the rowrank of the UniTensor Tin. For more details, please refer to the documentation of the function Svd_truncate(const Tensor &Tin, const cytnx_uint64 &keepdim, const double &err, const bool &is_UvT, const bool &return_err).

See also

Svd_truncate(const Tensor &Tin, const cytnx_uint64 &keepdim, const double &err, const bool &is_UvT, const bool &return_err)

Svd_truncate() [2/2]

std::vector< Tensor > cytnx::linalg::Svd_truncate	(	const Tensor &	Tin,
		const cytnx_uint64 &	keepdim,
		const double &	err = 0,
		const bool &	is_UvT = true,
		const bool &	return_err = false
	)

Perform the truncate Singular-Value decomposition on a rank-2 Tensor (a matrix).

This function will perform the truncate Singular-Value decomposition on a matrix (a rank-2 Tensor). It will perform the SVD first, and then truncate the singular values to the given cutoff err. That means givent a matrix Tin as \( M \), then the result will be:

\[ M = U S V^\dagger, \]

where \( S \) is a singular values matrix with the singular values truncated to the given cutoff err. The dimension of \( S \) is at most keepdim.

Parameters

[in]	Tin	a Tensor, it should be a rank-2 tensor (matrix)
[in]	keepdim	the number (at most) of singular values to keep.
[in]	err	the cutoff error (the singular values smaller than err will be truncated.)
[in]	is_UvT	whether need to return a left unitary matrix and a right unitary matrix.
[in]	return_err	whether need to return the error. If return_err is true, then the error will be pushed back to the vector. It is the smallest singular value in the singular values matrix \( S \).

Returns

[std::vector<Tensors>]

1. The first tensor is a 1-d tensor contanin the singular values
2. If is_UvT is true, then the tensor \( U,V^\dagger \) will be pushed back to the vector.
3. If return_err is true, then the error will be pushed back to the vector.

Precondition

The input tensor should be a rank-2 tensor (matrix).

See also

Svd

Tensordot()

Tensor cytnx::linalg::Tensordot	(	const Tensor &	Tl,
		const Tensor &	Tr,
		const std::vector< cytnx_uint64 > &	idxl,
		const std::vector< cytnx_uint64 > &	idxr,
		const bool &	cacheL = false,
		const bool &	cacheR = false
	)

perform tensor dot by sum out the indices assigned of two Tensors.

Parameters

[in]	Tl	Tensor #1
[in]	Tr	Tensor #2
[in]	idxl	the indices of rank of Tensor #1 that is going to sum with Tensor #2
[in]	idxr	the indices of rank of Tensor #2 that is going to sum with Tensor #1
[in]	cacheL	cache Tensor #1 (See user-guide for details)
[in]	cacheR	cache Tensor #2 (See user-guide for details)

Returns

[Tensor]

Note

1. the elements in idxl and idxr have one to one correspondence.
2. two tensors should on same device.

Tensordot_dg()

Tensor cytnx::linalg::Tensordot_dg	(	const Tensor &	Tl,
		const Tensor &	Tr,
		const std::vector< cytnx_uint64 > &	idxl,
		const std::vector< cytnx_uint64 > &	idxr,
		const bool &	diag_L
	)

perform tensor dot by sum out the indices assigned of two Tensors, with either one of them to be a rank-2 diagonal tensor represented by a rank-2 tensor.

Parameters

[in]	Tl	Tensor #1
[in]	Tr	Tensor #2
[in]	idxl	the indices of rank of Tensor #1 that is going to sum with Tensor #2
[in]	idxr	the indices of rank of Tensor #2 that is going to sum with Tensor #1
[in]	diag_L	if Tl(true)/Tr(false) is a diagnal matrix, represented by a rank-1 tensor.

Returns

[Tensor]

Note

1. the elements in idxl and idxr have one to one correspondence.
2. two tensors should on same device.
3. if diag_L=true, Tl should be a rank-1 tensor as the diagonal elements of a diagonal matrix. if false, Tr should be a rank-1 tensor

Trace() [1/4]

cytnx::UniTensor cytnx::linalg::Trace	(	const cytnx::UniTensor &	Tin,
		const cytnx_int64 &	a = 0,
		const cytnx_int64 &	b = 1
	)

Deprecated:

This function is deprecated, please use Trace(const cytnx::UniTensor &Tin, const string &a, const string &b) instead.

Trace() [2/4]

cytnx::UniTensor cytnx::linalg::Trace	(	const cytnx::UniTensor &	Tin,
		const cytnx_int64 &	a = 0,
		const cytnx_int64 &	b = 1,
		const bool &	by_label = false
	)

Deprecated:

This function is deprecated, please use Trace(const cytnx::UniTensor &Tin, const string &a, const string &b) instead.

Trace() [3/4]

cytnx::UniTensor cytnx::linalg::Trace	(	const cytnx::UniTensor &	Tin,
		const std::string &	a,
		const std::string &	b
	)

Perform trace over two legs of a UniTensor.

This function performs trace over two legs of a UniTensor Tin. The two legs are specified by a and b. For more details, please refer to the documentation of the function Trace(const Tensor &Tin, const cytnx_int64 &a, const cytnx_int64 &b).

See also

Trace(const Tensor &Tin, const cytnx_int64 &a, const cytnx_int64 &b)

Trace() [4/4]

Tensor cytnx::linalg::Trace	(	const Tensor &	Tn,
		const cytnx_uint64 &	axisA = 0,
		const cytnx_uint64 &	axisB = 1
	)

perform trace over index.

This function will perform trace over index axisA and axisB. For example, if Tn is a rank-4 tensor \( T \), then axisA = 0 and axisB = 2, then the result will be:

\[ \mathrm{Tr}_{j,l}(T) = \sum_{i,k} T_{i,j,k,l} \]

Parameters

[in]	Tn	a Tensor
[in]	axisA	the first index to perform trace.
[in]	axisB	the second index to perform trace.

Precondition

the Tn should be at-least rank-2 Tensor.

Tridiag()

std::vector< Tensor > cytnx::linalg::Tridiag	(	const Tensor &	Diag,
		const Tensor &	Sub_diag,
		const bool &	is_V = true,
		const bool &	is_row = false,
		bool	throw_excp = false
	)

perform diagonalization of symmetric tri-diagnoal matrix.

Parameters

Diag	Tensor #1
Sub_diag	Tensor #2
is_V	if calculate the eigen value.
k	Return k lowest eigen vector if is_V=True
throw_excp	Whether to throw exception when error occurs in Tridiag internal function

Returns

[vector<Tensor>] if is_V = True, the first tensor is the eigen value, and second tensor is eigenvector of shape [k,L].

Precondition

two Tensors must be Rank-1, with length of Diag = L and Sub_diag length = L-1.

Note

performance tune: This function have better performance when two vectors with same types, and are one of following type: cytnx_double, cytnx_float. In general all real type can be use as input, which will be promote to floating point type for calculation.

Vectordot()

Tensor cytnx::linalg::Vectordot	(	const Tensor &	Tl,
		const Tensor &	Tr,
		const bool &	is_conj = false
	)

perform inner product of vectors

Parameters

[in]	Tl	Tensor #1
[in]	Tr	Tensor #2
[in]	if	the Tl should be conjugated (only work for complex. For real Tensor, no function), default: false

Returns

[Tensor] Rank-0

Precondition

two Tensors must be Rank-1, with same length.

Note

performance tune: This function have better performance when two vectors with same types, and are one of following type: cytnx_double, cytnx_float, cytnx_complex64 or cytnx_complex128.