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CentOS 7.0 - man page for dlasd0 (centos section 3)

dlasd0.f(3)							      LAPACK							       dlasd0.f(3)

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 n-by-m matrix B with diagonal d and off-diagonal 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 n-by-m matrix B with diagonal d and off-diagonal e. Used by sbdsdc. Purpose: Using a divide and conquer approach, DLASD0 computes the singular value decomposition (SVD) of a real upper bidiagonal N-by-M 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. SQRE SQRE 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; D D 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. E E is DOUBLE PRECISION array, dimension (M-1) Contains the subdiagonal entries of the bidiagonal matrix. On exit, E has been destroyed. U U is DOUBLE PRECISION array, dimension at least (LDQ, N) On exit, U contains the left singular vectors. LDU LDU is INTEGER On entry, leading dimension of U. VT VT is DOUBLE PRECISION array, dimension at least (LDVT, M) On exit, VT**T contains the right singular vectors. LDVT LDVT is INTEGER On entry, leading dimension of VT. SMLSIZ SMLSIZ is INTEGER On entry, maximum size of the subproblems at the bottom of the computation tree. IWORK IWORK is INTEGER work array. Dimension must be at least (8 * N) WORK WORK is DOUBLE PRECISION work array. Dimension must be at least (3 * M**2 + 2 * M) INFO INFO is INTEGER = 0: successful exit. < 0: if INFO = -i, the i-th 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 Generated automatically by Doxygen for LAPACK from the source code. Version 3.4.2 Tue Sep 25 2012 dlasd0.f(3)