TESTING/EIG/dbdt05.f(3)    Library Functions Manual    TESTING/EIG/dbdt05.f(3)

NAME
       TESTING/EIG/dbdt05.f

SYNOPSIS
   Functions/Subroutines
       subroutine dbdt05 (m, n, a, lda, s, ns, u, ldu, vt, ldvt, work, resid)
           DBDT05

Function/Subroutine Documentation
   subroutine dbdt05 (integer m, integer n, double precision, dimension( lda,
       * ) a, integer lda, double precision, dimension( * ) s, integer ns,
       double precision, dimension( ldu, * ) u, integer ldu, double precision,
       dimension( ldvt, * ) vt, integer ldvt, double precision, dimension( * )
       work, double precision resid)
       DBDT05

       Purpose:


            DBDT05 reconstructs a bidiagonal matrix B from its (partial) SVD:
               S = U' * B * V
            where U and V are orthogonal matrices and S is diagonal.

            The test ratio to test the singular value decomposition is
               RESID = norm( S - U' * B * V ) / ( n * norm(B) * EPS )
            where VT = V' and EPS is the machine precision.

       Parameters
           M

                     M is INTEGER
                     The number of rows of the matrices A and U.

           N

                     N is INTEGER
                     The number of columns of the matrices A and VT.

           A

                     A is DOUBLE PRECISION array, dimension (LDA,N)
                     The m by n matrix A.

           LDA

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

           S

                     S is DOUBLE PRECISION array, dimension (NS)
                     The singular values from the (partial) SVD of B, sorted in
                     decreasing order.

           NS

                     NS is INTEGER
                     The number of singular values/vectors from the (partial)
                     SVD of B.

           U

                     U is DOUBLE PRECISION array, dimension (LDU,NS)
                     The n by ns orthogonal matrix U in S = U' * B * V.

           LDU

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

           VT

                     VT is DOUBLE PRECISION array, dimension (LDVT,N)
                     The n by ns orthogonal matrix V in S = U' * B * V.

           LDVT

                     LDVT is INTEGER
                     The leading dimension of the array VT.

           WORK

                     WORK is DOUBLE PRECISION array, dimension (M,N)

           RESID

                     RESID is DOUBLE PRECISION
                     The test ratio:  norm(S - U' * A * V) / ( n * norm(A) * EPS )

       Author
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

       Definition at line 125 of file dbdt05.f.

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

LAPACK                          Version 3.12.0         TESTING/EIG/dbdt05.f(3)