dlasd0 (3)  Linux Manuals
NAME
dlasd0.f 
SYNOPSIS
Functions/Subroutines
subroutine dlasd0 (N, SQRE, D, E, U, LDU, VT, LDVT, SMLSIZ, IWORK, WORK, INFO)
DLASD0 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 dlasd0 (integerN, integerSQRE, double precision, dimension( * )D, double precision, dimension( * )E, double precision, dimension( ldu, * )U, integerLDU, double precision, dimension( ldvt, * )VT, integerLDVT, integerSMLSIZ, integer, dimension( * )IWORK, double precision, dimension( * )WORK, integerINFO)
DLASD0 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, DLASD0 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, DLASDA, 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 DOUBLE PRECISION 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 DOUBLE PRECISION array, dimension (M1) Contains the subdiagonal entries of the bidiagonal matrix. On exit, E has been destroyed.
UU is DOUBLE PRECISION 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 DOUBLE PRECISION 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 work array. Dimension must be at least (8 * N)
WORKWORK is DOUBLE PRECISION work array. Dimension must be at least (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 152 of file dlasd0.f.
Author
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