Tensor Products

Detailed Description

These function are used for calculations with tensor products.

Data Structures
struct	TkData_t
	Tensor condensation state. More...

Functions
int	MatrixToVector (const Matrix_t *mat, Matrix_t *vecs, int n)
	Convert matrix to vector. More...
Matrix_t *	MatTensor (const Matrix_t *m1, const Matrix_t *m2)
	Tensor Product. More...
Matrix_t *	TensorMap (Matrix_t *vec, const Matrix_t *a, const Matrix_t *b)
	Map Under Tensor Product. More...
int	TK_ReadInfo (TkData_t *tki, const char *name)
	Read a .tki file. More...
int	TK_WriteInfo (TkData_t *tki, const char *name)
	Write a .tki file. More...
Matrix_t *	VectorToMatrix (Matrix_t *vecs, int n, int noc)
	Convert vector to matrix. More...

Function Documentation

int MatrixToVector	(	const Matrix_t *	mat,
		Matrix_t *	vecs,
		int	n
	)

Convert matrix to vector.

This function converts a matrix into a row vector by concatenating the rows of the matrix. If mat is a r by c matrix, the resulting vector has rc entries. Instead of allocating a new buffer for the result, MatToVec() expects a pointer to a matrix, vecs, and puts the vector into the n-th row of this matrix. Of course, vecs must be over the smae field as mat, have rc columns and at least n+1 rows.

See also

VectorToMatrix

Parameters

mat	Matrix to convert.
vecs	Destination of the vector.
n	Row number where the vector is stored.

Returns

0 on success, -1 on error.

Matrix_t* MatTensor	(	const Matrix_t *	m1,
		const Matrix_t *	m2
	)

Tensor Product.

This function calculates the (Kronecker) tensor product m1⊗m2. Both matrices must be over the same field.

Parameters

m1	Pointer to the first matrix.
m2	Pointer to the second matrix.

Returns

The tensor product of m1 and m2, or 0 on error.

Matrix_t* TensorMap	(	Matrix_t *	vec,
		const Matrix_t *	a,
		const Matrix_t *	b
	)

Map Under Tensor Product.

This function applies the tensor product of two matrices to one or more vectors. The same calculation could be done with MatMul() and MatTensor(), but this function is usually faster and uses less memory, because it does not calculate the full tensor product of a⊗b.

See also

VectorToMatrix() MatrixToVector()

Parameters

vec	Vectors to map.
a	Left matrix.
b	Right matrix.

Returns

Image of vec under a⊗b, or 0 on error.

int TK_ReadInfo	(	TkData_t *	tki,
		const char *	name
	)

Read a .tki file.

This function reads the contents of a .tki file and puts the data into a TkData_t structure.

Parameters

tki	Pointer to a TkData_t structure where the data is stored.
name	File name without ".tki" extension (which is appended automatically).

Returns

0 on success, -1 on error.

int TK_WriteInfo	(	TkData_t *	tki,
		const char *	name
	)

Write a .tki file.

This function writes the contents of a TkData_t structure into a file.

Parameters

tki	Pointer to a TkData_t structure.
name	File name without ".tki" extension (which is appended automatically).

Returns

0 o success, -1 on error.

Matrix_t* VectorToMatrix	(	Matrix_t *	vecs,
		int	n,
		int	noc
	)

Convert vector to matrix.

This function converts a vector with m=rc entries into a r by c matrix by filling the matrix from top to bottom and left to right with the entries of the vector. The vector is taken as the n-th row of vecs. A new matrix is allocated and returned. noc is the number of columns of the result, which must be a divisor of the number of columns of vecs.

See also

MatrixToVector

Parameters

vecs	List of vectors.
n	Number of the vector to convert.
noc	Desired number of columns.

Returns

0 on success, -1 on error.