• NAME
• SYNOPSIS
• F95 INTERFACE
• C INTERFACE
• PURPOSE
• ARGUMENTS

NAME

dsytrs - solve a system of linear equations A*X = B with a real symmetric matrix A using the factorization A = U*D*U**T or A = L*D*L**T computed by SSYTRF

SYNOPSIS

  SUBROUTINE DSYTRS( UPLO, N, NRHS, A, LDA, IPIVOT, B, LDB, INFO)
  CHARACTER * 1 UPLO
  INTEGER N, NRHS, LDA, LDB, INFO
  INTEGER IPIVOT(*)
  DOUBLE PRECISION A(LDA,*), B(LDB,*)

  SUBROUTINE DSYTRS_64( UPLO, N, NRHS, A, LDA, IPIVOT, B, LDB, INFO)
  CHARACTER * 1 UPLO
  INTEGER*8 N, NRHS, LDA, LDB, INFO
  INTEGER*8 IPIVOT(*)
  DOUBLE PRECISION A(LDA,*), B(LDB,*)

F95 INTERFACE

  SUBROUTINE SYTRS( UPLO, [N], [NRHS], A, [LDA], IPIVOT, B, [LDB], 
 *       [INFO])
  CHARACTER(LEN=1) :: UPLO
  INTEGER :: N, NRHS, LDA, LDB, INFO
  INTEGER, DIMENSION(:) :: IPIVOT
  REAL(8), DIMENSION(:,:) :: A, B

  SUBROUTINE SYTRS_64( UPLO, [N], [NRHS], A, [LDA], IPIVOT, B, [LDB], 
 *       [INFO])
  CHARACTER(LEN=1) :: UPLO
  INTEGER(8) :: N, NRHS, LDA, LDB, INFO
  INTEGER(8), DIMENSION(:) :: IPIVOT
  REAL(8), DIMENSION(:,:) :: A, B

C INTERFACE

#include <sunperf.h>

void dsytrs(char uplo, int n, int nrhs, double *a, int lda, int *ipivot, double *b, int ldb, int *info);

void dsytrs_64(char uplo, long n, long nrhs, double *a, long lda, long *ipivot, double *b, long ldb, long *info);

PURPOSE

dsytrs solves a system of linear equations A*X = B with a real symmetric matrix A using the factorization A = U*D*U**T or A = L*D*L**T computed by SSYTRF.

ARGUMENTS

• UPLO (input)
  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)
  The order of the matrix A. N > = 0.

• NRHS (input)
  The number of right hand sides, i.e., the number of columns of the matrix B. NRHS > = 0.

• A (input)
  The block diagonal matrix D and the multipliers used to obtain the factor U or L as computed by SSYTRF.

• LDA (input)
  The leading dimension of the array A. LDA > = max(1,N).

• IPIVOT (input)
  Details of the interchanges and the block structure of D as determined by SSYTRF.

• B (input/output)
  On entry, the right hand side matrix B. On exit, the solution matrix X.

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

• INFO (output)
  

   = 0:  successful exit

   < 0:  if INFO  = -i, the i-th argument had an illegal value