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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