dsttrs(3P) Sun Performance Library dsttrs(3P)NAMEdsttrs - computes the solution to a real system of linear equations A *
X = B
SYNOPSIS
SUBROUTINE DSTTRS(N, NRHS, L, D, SUBL, B, LDB, IPIV, INFO)
INTEGER N, NRHS, LDB, INFO
INTEGER IPIV(*)
DOUBLE PRECISION L(*), D(*), SUBL(*), B(LDB,*)
SUBROUTINE DSTTRS_64(N, NRHS, L, D, SUBL, B, LDB, IPIV, INFO)
INTEGER*8 N, NRHS, LDB, INFO
INTEGER*8 IPIV(*)
DOUBLE PRECISION L(*), D(*), SUBL(*), B(LDB,*)
F95 INTERFACE
SUBROUTINE STTRS([N], [NRHS], L, D, SUBL, B, [LDB], IPIV, [INFO])
INTEGER :: N, NRHS, LDB, INFO
INTEGER, DIMENSION(:) :: IPIV
REAL(8), DIMENSION(:) :: L, D, SUBL
REAL(8), DIMENSION(:,:) :: B
SUBROUTINE STTRS_64([N], [NRHS], L, D, SUBL, B, [LDB], IPIV, [INFO])
INTEGER(8) :: N, NRHS, LDB, INFO
INTEGER(8), DIMENSION(:) :: IPIV
REAL(8), DIMENSION(:) :: L, D, SUBL
REAL(8), DIMENSION(:,:) :: B
C INTERFACE
#include <sunperf.h>
void dsttrs(int n, int nrhs, double *l, double *d, double *subl, double
*b, int ldb, int *ipiv, int *info);
void dsttrs_64(long n, long nrhs, double *l, double *d, double *subl,
double *b, long ldb, long *ipiv, long *info);
PURPOSEdsttrs computes the solution to a real system of linear equations A * X
= B, where A is an N-by-N symmetric tridiagonal matrix and X and B are
N-by-NRHS matrices.
ARGUMENTS
N (input)
INTEGER
The order of the matrix A. N >= 0.
NRHS (input)
INTEGER
The number of right hand sides, i.e., the number of columns
of the matrix B. NRHS >= 0.
L (input)
REAL array, dimension (N-1)
On entry, the subdiagonal elements of L.
D (input)
REAL array, dimension (N)
On entry, the diagonal elements of D.
SUBL (input)
REAL array, dimension (N-2)
On entry, the second subdiagonal elements of L.
B (input/output)
REAL array, dimension
(LDB, NRHS) On entry, the N-by-NRHS right hand side matrix B.
On exit, if INFO = 0, the N-by-NRHS solution matrix X.
LDB (input)
INTEGER
The leading dimension of the array B. LDB >= max(1, N)
IPIV (input)
INTEGER array, dimension (N)
Details of the interchanges and block pivot. IPIV is provided
by DSTTRF. If IPIV(K) > 0, 1 by 1 pivot, and if IPIV(K) = K +
1 an interchange done; If IPIV(K) < 0, 2 by 2 pivot, no
interchange required.
INFO (output)
INTEGER
= 0: successful exit
< 0: if INFO = -k, the k-th argument had an illegal value
6 Mar 2009 dsttrs(3P)
