dgetrs(3S)

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 DGETRF

SYNOPSIS
     SUBROUTINE DGETRS( TRANS, N, NRHS, A, LDA, IPIV, B, LDB, INFO )

         CHARACTER      TRANS

         INTEGER        INFO, LDA, LDB, N, NRHS

         INTEGER        IPIV( * )

         DOUBLE         PRECISION A( LDA, * ), B( LDB, * )

IMPLEMENTATION
     These routines are part of the SCSL Scientific Library and can be loaded
     using either the -lscs or the -lscs_mp option.  The -lscs_mp option
     directs the linker to use the multi-processor version of the library.

     When linking to SCSL with -lscs or -lscs_mp, the default integer size is
     4 bytes (32 bits). Another version of SCSL is available in which integers
     are 8 bytes (64 bits).  This version allows the user access to larger
     memory sizes and helps when porting legacy Cray codes.  It can be loaded
     by using the -lscs_i8 option or the -lscs_i8_mp option. A program may use
     only one of the two versions; 4-byte integer and 8-byte integer library
     calls cannot be mixed.

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 DGETRF.

ARGUMENTS
     TRANS   (input) CHARACTER*1
             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) 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.

     A       (input) DOUBLE PRECISION array, dimension (LDA,N)
             The factors L and U from the factorization A = P*L*U as computed
             by DGETRF.
     LDA     (input) INTEGER
             The leading dimension of the array A.  LDA >= max(1,N).

     IPIV    (input) INTEGER array, dimension (N)
             The pivot indices from DGETRF; for 1<=i<=N, row i of the matrix
             was interchanged with row IPIV(i).

     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

SEE ALSO
     INTRO_LAPACK(3S), INTRO_SCSL(3S)

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