Scroll to navigation

/home/abuild/rpmbuild/BUILD/lapack-3.12.0/TESTING/EIG/sbdt04.f(3) Library Functions Manual /home/abuild/rpmbuild/BUILD/lapack-3.12.0/TESTING/EIG/sbdt04.f(3)

NAME

/home/abuild/rpmbuild/BUILD/lapack-3.12.0/TESTING/EIG/sbdt04.f

SYNOPSIS

Functions/Subroutines


subroutine SBDT04 (uplo, n, d, e, s, ns, u, ldu, vt, ldvt, work, resid)
SBDT04

Function/Subroutine Documentation

subroutine SBDT04 (character uplo, integer n, real, dimension( * ) d, real, dimension( * ) e, real, dimension( * ) s, integer ns, real, dimension( ldu, * ) u, integer ldu, real, dimension( ldvt, * ) vt, integer ldvt, real, dimension( * ) work, real resid)

SBDT04

Purpose:

!>
!> SBDT04 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 REAL array, dimension (N)
!>          The n diagonal elements of the bidiagonal matrix B.
!> 

E

!>          E is REAL 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 REAL 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 REAL 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 REAL 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 REAL array, dimension (2*N)
!> 

RESID

!>          RESID is REAL
!>          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 sbdt04.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Version 3.12.0 LAPACK