TESTING/EIG/zunt01.f(3)

NAME
TESTING/EIG/zunt01.f

SYNOPSIS

  Functions/Subroutines
subroutine zunt01 (rowcol, m, n, u, ldu, work, lwork, rwork, resid)
ZUNT01

Function/Subroutine Documentation

  subroutine zunt01 (character rowcol, integer m, integer n, complex*16, dimension( ldu, * ) u, integer ldu, complex*16, dimension( * ) work, integer lwork, double precision, dimension( * ) rwork, double precision resid)

ZUNT01

Purpose:

     ZUNT01 checks that the matrix U is unitary by computing the ratio
        RESID = norm( I - U*U' ) / ( n * EPS ), if ROWCOL = 'R',
     or
        RESID = norm( I - U'*U ) / ( m * EPS ), if ROWCOL = 'C'.
     Alternatively, if there isn't sufficient workspace to form
     I - U*U' or I - U'*U, the ratio is computed as
        RESID = abs( I - U*U' ) / ( n * EPS ), if ROWCOL = 'R',
     or
        RESID = abs( I - U'*U ) / ( m * EPS ), if ROWCOL = 'C'.
     where EPS is the machine precision.  ROWCOL is used only if m = n;
     if m > n, ROWCOL is assumed to be 'C', and if m < n, ROWCOL is
     assumed to be 'R'.

Parameters
    ROWCOL

              ROWCOL is CHARACTER
              Specifies whether the rows or columns of U should be checked
              for orthogonality.  Used only if M = N.
              = 'R':  Check for orthogonal rows of U
              = 'C':  Check for orthogonal columns of U

    M

              M is INTEGER
              The number of rows of the matrix U.

    N

              N is INTEGER
              The number of columns of the matrix U.

    U

              U is COMPLEX*16 array, dimension (LDU,N)
              The unitary matrix U.  U is checked for orthogonal columns
              if m > n or if m = n and ROWCOL = 'C'.  U is checked for
              orthogonal rows if m < n or if m = n and ROWCOL = 'R'.

    LDU

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

    WORK

              WORK is COMPLEX*16 array, dimension (LWORK)

    LWORK

              LWORK is INTEGER
              The length of the array WORK.  For best performance, LWORK
              should be at least N*N if ROWCOL = 'C' or M*M if
              ROWCOL = 'R', but the test will be done even if LWORK is 0.

    RWORK

              RWORK is DOUBLE PRECISION array, dimension (min(M,N))
              Used only if LWORK is large enough to use the Level 3 BLAS
              code.

    RESID

              RESID is DOUBLE PRECISION
              RESID = norm( I - U * U' ) / ( n * EPS ), if ROWCOL = 'R', or
              RESID = norm( I - U' * U ) / ( m * EPS ), if ROWCOL = 'C'.

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 124 of file zunt01.f.

Author

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