TESTING/LIN/zqrt14.f(3)

NAME
TESTING/LIN/zqrt14.f

SYNOPSIS

  Functions/Subroutines
double precision function zqrt14 (trans, m, n, nrhs, a, lda, x, ldx, work, lwork)
ZQRT14

Function/Subroutine Documentation

  double precision function zqrt14 (character trans, integer m, integer n, integer nrhs, complex*16, dimension( lda, * ) a, integer lda, complex*16, dimension( ldx, * ) x, integer ldx, complex*16, dimension( lwork ) work, integer lwork)

ZQRT14

Purpose:

    !>
    !> ZQRT14 checks whether X is in the row space of A or A'.  It does so
    !> by scaling both X and A such that their norms are in the range
    !> [sqrt(eps), 1/sqrt(eps)], then computing a QR factorization of [A,X]
    !> (if TRANS = 'C') or an LQ factorization of [A',X]' (if TRANS = 'N'),
    !> and returning the norm of the trailing triangle, scaled by
    !> MAX(M,N,NRHS)*eps.
    !>

Parameters
    TRANS

    !>          TRANS is CHARACTER*1
    !>          = 'N':  No transpose, check for X in the row space of A
    !>          = 'C':  Conjugate transpose, check for X in row space of A'.
    !>

    M

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

    N

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

    NRHS

    !>          NRHS is INTEGER
    !>          The number of right hand sides, i.e., the number of columns
    !>          of X.
    !>

    A

    !>          A is COMPLEX*16 array, dimension (LDA,N)
    !>          The M-by-N matrix A.
    !>

    LDA

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

    X

    !>          X is COMPLEX*16 array, dimension (LDX,NRHS)
    !>          If TRANS = 'N', the N-by-NRHS matrix X.
    !>          IF TRANS = 'C', the M-by-NRHS matrix X.
    !>

    LDX

    !>          LDX is INTEGER
    !>          The leading dimension of the array X.
    !>

    WORK

    !>          WORK is COMPLEX*16 array dimension (LWORK)
    !>

    LWORK

    !>          LWORK is INTEGER
    !>          length of workspace array required
    !>          If TRANS = 'N', LWORK >= (M+NRHS)*(N+2);
    !>          if TRANS = 'C', LWORK >= (N+NRHS)*(M+2).
    !>

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 114 of file zqrt14.f.

Author

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