TESTING/LIN/dqrt17.f(3)    Library Functions Manual    TESTING/LIN/dqrt17.f(3)

NAME
       TESTING/LIN/dqrt17.f

SYNOPSIS
   Functions/Subroutines
       double precision function dqrt17 (trans, iresid, m, n, nrhs, a, lda, x,
           ldx, b, ldb, c, work, lwork)
           DQRT17

Function/Subroutine Documentation
   double precision function dqrt17 (character trans, integer iresid, integer
       m, integer n, integer nrhs, double precision, dimension( lda, * ) a,
       integer lda, double precision, dimension( ldx, * ) x, integer ldx,
       double precision, dimension( ldb, * ) b, integer ldb, double precision,
       dimension( ldb, * ) c, double precision, dimension( lwork ) work,
       integer lwork)
       DQRT17

       Purpose:


            DQRT17 computes the ratio

               norm(R**T * op(A)) / ( norm(A) * alpha * max(M,N,NRHS) * EPS ),

            where R = B - op(A)*X, op(A) is A or A**T, depending on TRANS, EPS
            is the machine epsilon, and

               alpha = norm(B) if IRESID = 1 (zero-residual problem)
               alpha = norm(R) if IRESID = 2 (otherwise).

            The norm used is the 1-norm.

       Parameters
           TRANS

                     TRANS is CHARACTER*1
                     Specifies whether or not the transpose of A is used.
                     = 'N':  No transpose, op(A) = A.
                     = 'T':  Transpose, op(A) = A**T.

           IRESID

                     IRESID is INTEGER
                     IRESID = 1 indicates zero-residual problem.
                     IRESID = 2 indicates non-zero residual.

           M

                     M is INTEGER
                     The number of rows of the matrix A.
                     If TRANS = 'N', the number of rows of the matrix B.
                     If TRANS = 'T', the number of rows of the matrix X.

           N

                     N is INTEGER
                     The number of columns of the matrix  A.
                     If TRANS = 'N', the number of rows of the matrix X.
                     If TRANS = 'T', the number of rows of the matrix B.

           NRHS

                     NRHS is INTEGER
                     The number of columns of the matrices X and B.

           A

                     A is DOUBLE PRECISION array, dimension (LDA,N)
                     The m-by-n matrix A.

           LDA

                     LDA is INTEGER
                     The leading dimension of the array A. LDA >= M.

           X

                     X is DOUBLE PRECISION array, dimension (LDX,NRHS)
                     If TRANS = 'N', the n-by-nrhs matrix X.
                     If TRANS = 'T', the m-by-nrhs matrix X.

           LDX

                     LDX is INTEGER
                     The leading dimension of the array X.
                     If TRANS = 'N', LDX >= N.
                     If TRANS = 'T', LDX >= M.

           B

                     B is DOUBLE PRECISION array, dimension (LDB,NRHS)
                     If TRANS = 'N', the m-by-nrhs matrix B.
                     If TRANS = 'T', the n-by-nrhs matrix B.

           LDB

                     LDB is INTEGER
                     The leading dimension of the array B.
                     If TRANS = 'N', LDB >= M.
                     If TRANS = 'T', LDB >= N.

           C

                     C is DOUBLE PRECISION array, dimension (LDB,NRHS)

           WORK

                     WORK is DOUBLE PRECISION array, dimension (LWORK)

           LWORK

                     LWORK is INTEGER
                     The length of the array WORK.  LWORK >= NRHS*(M+N).

       Author
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

       Definition at line 151 of file dqrt17.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

LAPACK                          Version 3.12.0         TESTING/LIN/dqrt17.f(3)