NAME

dsptrs - solve a system of linear equations A∗X = B with a real symmetric matrix A stored in packed format using the factorization A = U∗D∗U∗∗T or A = L∗D∗L∗∗T computed by DSPTRF

SYNOPSIS

SUBROUTINE DSPTRS( UPLO, N, NRHS, AP, IPIV, B, LDB, INFO )

CHARACTER UPLO

INTEGER INFO, LDB, N, NRHS

INTEGER IPIV( ∗ )

DOUBLE PRECISION AP( ∗ ), B( LDB, ∗ )

#include <sunperf.h>

void dsptrs(char uplo, int n, int nrhs, double ∗dap, int ∗ipivot, double ∗db, int ldb, int ∗info) ;

PURPOSE

DSPTRS solves a system of linear equations A∗X = B with a real symmetric matrix A stored in packed format using the factorization A = U∗D∗U∗∗T or A = L∗D∗L∗∗T computed by DSPTRF. 
 

ARGUMENTS

UPLO (input) CHARACTER∗1
Specifies whether the details of the factorization are stored as an upper or lower triangular matrix. = ’U’:  Upper triangular, form is A = U∗D∗U∗∗T;
= ’L’:  Lower triangular, form is A = L∗D∗L∗∗T.

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.

AP (input) DOUBLE PRECISION array, dimension (N∗(N+1)/2)
The block diagonal matrix D and the multipliers used to obtain the factor U or L as computed by DSPTRF, stored as a packed triangular matrix.

IPIV (input) INTEGER array, dimension (N)
Details of the interchanges and the block structure of D as determined by DSPTRF.

B (input/output) DOUBLE PRECISION array, dimension (LDB,NRHS)
On entry, the right hand side matrix B. On exit, the solution matrix X.

LDB (input) INTEGER
The leading dimension of the array B.  LDB >= max(1,N).

INFO (output) INTEGER
= 0:  successful exit
< 0: if INFO = -i, the i-th argument had an illegal value

SunOS 5.0  —  Last change: 10 Dec 1998