sbdt04.f - Man Page
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.
Referenced By
The man page sbdt04(3) is an alias of sbdt04.f(3).
Tue Nov 28 2023 12:08:42 Version 3.12.0 LAPACK