HPL_dtrsm(3) HPL Library Functions HPL_dtrsm(3)NAMEHPL_dtrsm - B := A^{-1} * B or B := B * A^{-1}.
SYNOPSIS
#include "hpl.h"
void HPL_dtrsm( const enum HPL_ORDER ORDER, const enum HPL_SIDE SIDE,
const enum HPL_UPLO UPLO, const enum HPL_TRANS TRANS, const enum
HPL_DIAG DIAG, const int M, const int N, const double ALPHA, const dou‐
ble * A, const int LDA, double * B, const int LDB );
DESCRIPTIONHPL_dtrsm solves one of the matrix equations
op( A ) * X = alpha * B, or X * op( A ) = alpha * B,
where alpha is a scalar, X and B are m by n matrices, A is a unit, or
non-unit, upper or lower triangular matrix and op(A) is one of
op( A ) = A or op( A ) = A^T.
The matrix X is overwritten on B.
No test for singularity or near-singularity is included in this
routine. Such tests must be performed before calling this routine.
ARGUMENTS
ORDER (local input) const enum HPL_ORDER
On entry, ORDER specifies the storage format of the operands
as follows:
ORDER = HplRowMajor,
ORDER = HplColumnMajor.
SIDE (local input) const enum HPL_SIDE
On entry, SIDE specifies whether op(A) appears on the left
or right of X as follows:
SIDE==HplLeft op( A ) * X = alpha * B,
SIDE==HplRight X * op( A ) = alpha * B.
UPLO (local input) const enum HPL_UPLO
On entry, UPLO specifies whether the upper or lower
triangular part of the array A is to be referenced. When
UPLO==HplUpper, only the upper triangular part of A is to be
referenced, otherwise only the lower triangular part of A is to
be referenced.
TRANS (local input) const enum HPL_TRANS
On entry, TRANSA specifies the form of op(A) to be used in
the matrix-matrix operation follows:
TRANSA==HplNoTrans : op( A ) = A,
TRANSA==HplTrans : op( A ) = A^T,
TRANSA==HplConjTrans : op( A ) = A^T.
DIAG (local input) const enum HPL_DIAG
On entry, DIAG specifies whether A is unit triangular or
not. When DIAG==HplUnit, A is assumed to be unit triangular,
and otherwise, A is not assumed to be unit triangular.
M (local input) const int
On entry, M specifies the number of rows of the matrix B.
M must be at least zero.
N (local input) const int
On entry, N specifies the number of columns of the matrix B.
N must be at least zero.
ALPHA (local input) const double
On entry, ALPHA specifies the scalar alpha. When ALPHA is
supplied as zero then the elements of the matrix B need not
be set on input.
A (local input) const double *
On entry, A points to an array of size equal to or greater
than LDA * k, where k is m when SIDE==HplLeft and is n
otherwise. Before entry with UPLO==HplUpper, the leading k
by k upper triangular part of the array A must contain the
upper triangular matrix and the strictly lower triangular
part of A is not referenced. When UPLO==HplLower on entry,
the leading k by k lower triangular part of the array A must
contain the lower triangular matrix and the strictly upper
triangular part of A is not referenced.
Note that when DIAG==HplUnit, the diagonal elements of A
not referenced either, but are assumed to be unity.
LDA (local input) const int
On entry, LDA specifies the leading dimension of A as
declared in the calling (sub) program. LDA must be at
least MAX(1,m) when SIDE==HplLeft, and MAX(1,n) otherwise.
B (local input/output) double *
On entry, B points to an array of size equal to or greater
than LDB * n. Before entry, the leading m by n part of the
array B must contain the matrix B, except when beta is zero,
in which case B need not be set on entry. On exit, the array B
is overwritten by the m by n solution matrix.
LDB (local input) const int
On entry, LDB specifies the leading dimension of B as
declared in the calling (sub) program. LDB must be at
least MAX(1,m).
EXAMPLE
#include "hpl.h"
int main(int argc, char *argv[])
{
double a[2*2], b[2*2];
a[0] = 4.0; a[1] = 1.0; a[2] = 2.0; a[3] = 5.0;
b[0] = 2.0; b[1] = 1.0; b[2] = 1.0; b[3] = 2.0;
HPL_dtrsm( HplColumnMajor, HplLeft, HplUpper,
HplNoTrans, HplNonUnit, 2, 2, 2.0,
a, 2, b, 2 );
printf(" [%f,%f]\n", b[0], b[2]);
printf("b=[%f,%f]\n", b[1], b[3]);
exit(0); return(0);
}
SEE ALSO
HPL_dgemm (3).
HPL 2.1 October 26, 2012 HPL_dtrsm(3)
