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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