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dgetrs

 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 factori-
      zation 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, * )

 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).

 (LDB,NRHS)
      B       (input/output) DOUBLE PRECISION array, dimension
              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