dbdt05.f - Man Page

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.

Referenced By

The man page dbdt05(3) is an alias of dbdt05.f(3).

Tue Nov 28 2023 12:08:42 Version 3.12.0 LAPACK