(S|D|C|Z)POTRS¶

Single, double, single complex, and double complex POTRS.

Description¶

Solves a system of linear equations for multiple right-hand sides given the Cholesky factorization of the matrix.

Solves:

$A \mult X = B$

If UPLO is ‘U’ then A has been factored using an upper triangular matrix U:

$A = \herm{U} \mult U$

If UPLO is ‘L’ then A has been factored using a lower triangular matrix L:

$A = L \mult \herm{L}$

The factored form is used to solve the system of equations. Only the upper or lower triangular part of A is referenced.

To get the Cholesky factorization of a matrix use POTRF.

LAPACK Interface¶

void spotrs(const char *UPLO, const qml_long *N, const qml_long *NRHS, float *A,
    const qml_long *LDA, float *B, const qml_long *LDB, qml_long *INFO);

void dpotrs(const char *UPLO, const qml_long *N, const qml_long *NRHS, double *A,
    const qml_long *LDA, double *B, const qml_long *LDB, qml_long *INFO);

void cpotrs(const char *UPLO, const qml_long *N, const qml_long *NRHS,
    qml_single_complex *A, const qml_long *LDA, qml_single_complex *B,
    const qml_long *LDB, qml_long *INFO);

void zpotrs(const char *UPLO, const qml_long *N, const qml_long *NRHS,
    qml_double_complex *A, const qml_long *LDA, qml_double_complex *B,
    const qml_long *LDB, qml_long *INFO);

Arguments¶

UPLO	Specify whether A has been factored in ‘U’ upper triangular or ‘L’ lower triangular form
N	Number of linear equations, order of the matrix A
NRHS	Number of right hand sides, number of columns of B
A	Matrix of size N x N in factored form
LDA	Leading dimension of A
B	On entry, the N x NRHS matrix B, on exit the solution matrix
LDB	Leading dimension of B
INFO	0 on success, <0 on illegal arguments