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/home/abuild/rpmbuild/BUILD/lapack-3.12.0/TESTING/EIG/dbdt04.f(3) Library Functions Manual /home/abuild/rpmbuild/BUILD/lapack-3.12.0/TESTING/EIG/dbdt04.f(3)

NAME

/home/abuild/rpmbuild/BUILD/lapack-3.12.0/TESTING/EIG/dbdt04.f

SYNOPSIS

Functions/Subroutines


subroutine DBDT04 (uplo, n, d, e, s, ns, u, ldu, vt, ldvt, work, resid)
DBDT04

Function/Subroutine Documentation

subroutine DBDT04 (character uplo, integer n, double precision, dimension( * ) d, double precision, dimension( * ) e, 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)

DBDT04

Purpose:

!>
!> DBDT04 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

UPLO

!>          UPLO is CHARACTER*1
!>          Specifies whether the matrix B is upper or lower bidiagonal.
!>          = 'U':  Upper bidiagonal
!>          = 'L':  Lower bidiagonal
!> 

N

!>          N is INTEGER
!>          The order of the matrix B.
!> 

D

!>          D is DOUBLE PRECISION array, dimension (N)
!>          The n diagonal elements of the bidiagonal matrix B.
!> 

E

!>          E is DOUBLE PRECISION array, dimension (N-1)
!>          The (n-1) superdiagonal elements of the bidiagonal matrix B
!>          if UPLO = 'U', or the (n-1) subdiagonal elements of B if
!>          UPLO = 'L'.
!> 

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 (2*N)
!> 

RESID

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

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 129 of file dbdt04.f.

Author

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Version 3.12.0 LAPACK