slasd0 (3)  Linux Manuals
NAME
slasd0.f 
SYNOPSIS
Functions/Subroutines
subroutine slasd0 (N, SQRE, D, E, U, LDU, VT, LDVT, SMLSIZ, IWORK, WORK, INFO)
SLASD0 computes the singular values of a real upper bidiagonal nbym matrix B with diagonal d and offdiagonal e. Used by sbdsdc.
Function/Subroutine Documentation
subroutine slasd0 (integerN, integerSQRE, real, dimension( * )D, real, dimension( * )E, real, dimension( ldu, * )U, integerLDU, real, dimension( ldvt, * )VT, integerLDVT, integerSMLSIZ, integer, dimension( * )IWORK, real, dimension( * )WORK, integerINFO)
SLASD0 computes the singular values of a real upper bidiagonal nbym matrix B with diagonal d and offdiagonal e. Used by sbdsdc.
Purpose:

Using a divide and conquer approach, SLASD0 computes the singular value decomposition (SVD) of a real upper bidiagonal NbyM matrix B with diagonal D and offdiagonal E, where M = N + SQRE. The algorithm computes orthogonal matrices U and VT such that B = U * S * VT. The singular values S are overwritten on D. A related subroutine, SLASDA, computes only the singular values, and optionally, the singular vectors in compact form.
Parameters:

N
N is INTEGER On entry, the row dimension of the upper bidiagonal matrix. This is also the dimension of the main diagonal array D.
SQRESQRE is INTEGER Specifies the column dimension of the bidiagonal matrix. = 0: The bidiagonal matrix has column dimension M = N; = 1: The bidiagonal matrix has column dimension M = N+1;
DD is REAL array, dimension (N) On entry D contains the main diagonal of the bidiagonal matrix. On exit D, if INFO = 0, contains its singular values.
EE is REAL array, dimension (M1) Contains the subdiagonal entries of the bidiagonal matrix. On exit, E has been destroyed.
UU is REAL array, dimension at least (LDQ, N) On exit, U contains the left singular vectors.
LDULDU is INTEGER On entry, leading dimension of U.
VTVT is REAL array, dimension at least (LDVT, M) On exit, VT**T contains the right singular vectors.
LDVTLDVT is INTEGER On entry, leading dimension of VT.
SMLSIZSMLSIZ is INTEGER On entry, maximum size of the subproblems at the bottom of the computation tree.
IWORKIWORK is INTEGER array, dimension (8*N)
WORKWORK is REAL array, dimension (3*M**2+2*M)
INFOINFO is INTEGER = 0: successful exit. < 0: if INFO = i, the ith argument had an illegal value. > 0: if INFO = 1, a singular value did not converge
Author:

Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
 September 2012
Contributors:
 Ming Gu and Huan Ren, Computer Science Division, University of California at Berkeley, USA
Definition at line 150 of file slasd0.f.
Author
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