TESTING/EIG/dort01.f(3)    Library Functions Manual    TESTING/EIG/dort01.f(3)

NAME
       TESTING/EIG/dort01.f

SYNOPSIS
   Functions/Subroutines
       subroutine dort01 (rowcol, m, n, u, ldu, work, lwork, resid)
           DORT01

Function/Subroutine Documentation
   subroutine dort01 (character rowcol, integer m, integer n, double
       precision, dimension( ldu, * ) u, integer ldu, double precision,
       dimension( * ) work, integer lwork, double precision resid)
       DORT01

       Purpose:


            DORT01 checks that the matrix U is orthogonal 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 DOUBLE PRECISION array, dimension (LDU,N)
                     The orthogonal 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 DOUBLE PRECISION array, dimension (LWORK)

           LWORK

                     LWORK is INTEGER
                     The length of the array WORK.  For best performance, LWORK
                     should be at least N*(N+1) if ROWCOL = 'C' or M*(M+1) if
                     ROWCOL = 'R', but the test will be done even if LWORK is 0.

           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 115 of file dort01.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

LAPACK                          Version 3.12.0         TESTING/EIG/dort01.f(3)