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

NAME

dgetrs - solve a system of linear equations A * X = B or A' * X = B with a general N-by-N matrix A using the LU factorization computed by SGETRF

SYNOPSIS

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

  SUBROUTINE DGETRS_64( TRANSA, N, NRHS, A, LDA, IPIVOT, B, LDB, INFO)
  CHARACTER * 1 TRANSA
  INTEGER*8 N, NRHS, LDA, LDB, INFO
  INTEGER*8 IPIVOT(*)
  DOUBLE PRECISION A(LDA,*), B(LDB,*)

F95 INTERFACE

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

  SUBROUTINE GETRS_64( [TRANSA], [N], [NRHS], A, [LDA], IPIVOT, B, 
 *       [LDB], [INFO])
  CHARACTER(LEN=1) :: TRANSA
  INTEGER(8) :: N, NRHS, LDA, LDB, INFO
  INTEGER(8), DIMENSION(:) :: IPIVOT
  REAL(8), DIMENSION(:,:) :: A, B

C INTERFACE

#include <sunperf.h>

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

void dgetrs_64(char transa, long n, long nrhs, double *a, long lda, long *ipivot, double *b, long ldb, long *info);

PURPOSE

dgetrs solves a system of linear equations A * X = B or A' * X = B with a general N-by-N matrix A using the LU factorization computed by SGETRF.

ARGUMENTS

• TRANSA (input)
  Specifies the form of the system of equations:

   = 'N':  A * X  = B  (No transpose)

   = 'T':  A'* X  = B  (Transpose)

   = 'C':  A'* X  = B  (Conjugate transpose  = Transpose)

• 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 factors L and U from the factorization A = P*L*U as computed by SGETRF.

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

• IPIVOT (input)
  The pivot indices from SGETRF; for 1 < =i < =N, row i of the matrix was interchanged with row IPIVOT(i).

• 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