Contents

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

NAME

     zgetrs - solve a system of linear equations  A * X = B, A**T
     *  X  =  B,  or  A**H * X = B with a general N-by-N matrix A
     using the LU factorization computed by CGETRF

SYNOPSIS

     SUBROUTINE ZGETRS(TRANSA, N, NRHS, A, LDA, IPIVOT, B, LDB, INFO)

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

     SUBROUTINE ZGETRS_64(TRANSA, N, NRHS, A, LDA, IPIVOT, B, LDB, INFO)

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

  F95 INTERFACE
     SUBROUTINE GETRS([TRANSA], [N], [NRHS], A, [LDA], IPIVOT, B, [LDB],
            [INFO])

     CHARACTER(LEN=1) :: TRANSA
     COMPLEX(8), DIMENSION(:,:) :: A, B
     INTEGER :: N, NRHS, LDA, LDB, INFO
     INTEGER, DIMENSION(:) :: IPIVOT

     SUBROUTINE GETRS_64([TRANSA], [N], [NRHS], A, [LDA], IPIVOT, B, [LDB],
            [INFO])

     CHARACTER(LEN=1) :: TRANSA
     COMPLEX(8), DIMENSION(:,:) :: A, B
     INTEGER(8) :: N, NRHS, LDA, LDB, INFO
     INTEGER(8), DIMENSION(:) :: IPIVOT

  C INTERFACE
     #include <sunperf.h>

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

     void zgetrs_64(char transa, long n, long nrhs, doublecomplex
               *a, long lda, long *ipivot, doublecomplex *b, long
               ldb, long *info);

PURPOSE

     zgetrs solves a system of linear equations
        A * X = B,  A**T * X = B,  or  A**H * X = B with  a  gen-
     eral  N-by-N matrix A using the LU factorization computed by
     CGETRF.

ARGUMENTS

     TRANSA (input)
               Specifies the form of the system of equations:
               = 'N':  A * X = B     (No transpose)
               = 'T':  A**T * X = B  (Transpose)
               = 'C':  A**H * X = B  (Conjugate transpose)

               TRANSA is defaulted to 'N' for F95 INTERFACE.

     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 CGETRF.

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

     IPIVOT (input)
               The pivot indices from CGETRF; 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 ille-
               gal value