TESTING/LIN/dqrt16.f(3)

NAME
TESTING/LIN/dqrt16.f

SYNOPSIS

  Functions/Subroutines
subroutine dqrt16 (trans, m, n, nrhs, a, lda, x, ldx, b, ldb, rwork, resid)
DQRT16

Function/Subroutine Documentation

  subroutine dqrt16 (character trans, 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( * ) rwork, double precision resid)

DQRT16

Purpose:

     DQRT16 computes the residual for a solution of a system of linear
     equations  A*x = b  or  A'*x = b:
        RESID = norm(B - A*X) / ( max(m,n) * norm(A) * norm(X) * EPS ),
     where EPS is the machine epsilon.

Parameters
    TRANS

              TRANS is CHARACTER*1
              Specifies the form of the system of equations:
              = 'N':  A *x = b
              = 'T':  A'*x = b, where A' is the transpose of A
              = 'C':  A'*x = b, where A' is the transpose of A

    M

              M is INTEGER
              The number of rows of the matrix A.  M >= 0.

    N

              N is INTEGER
              The number of columns of the matrix A.  N >= 0.

    NRHS

              NRHS is INTEGER
              The number of columns of B, the matrix of right hand sides.
              NRHS >= 0.

    A

              A is DOUBLE PRECISION array, dimension (LDA,N)
              The original M x N matrix A.

    LDA

              LDA is INTEGER
              The leading dimension of the array A.  LDA >= max(1,M).

    X

              X is DOUBLE PRECISION array, dimension (LDX,NRHS)
              The computed solution vectors for the system of linear
              equations.

    LDX

              LDX is INTEGER
              The leading dimension of the array X.  If TRANS = 'N',
              LDX >= max(1,N); if TRANS = 'T' or 'C', LDX >= max(1,M).

    B

              B is DOUBLE PRECISION array, dimension (LDB,NRHS)
              On entry, the right hand side vectors for the system of
              linear equations.
              On exit, B is overwritten with the difference B - A*X.

    LDB

              LDB is INTEGER
              The leading dimension of the array B.  IF TRANS = 'N',
              LDB >= max(1,M); if TRANS = 'T' or 'C', LDB >= max(1,N).

    RWORK

              RWORK is DOUBLE PRECISION array, dimension (M)

    RESID

              RESID is DOUBLE PRECISION
              The maximum over the number of right hand sides of
              norm(B - A*X) / ( max(m,n) * norm(A) * norm(X) * EPS ).

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 131 of file dqrt16.f.

Author

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