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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)
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 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.
N
SQRE
D
E
U
LDU
VT
LDVT
SMLSIZ
IWORK
WORK
INFO
Author:
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 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 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 is DOUBLE PRECISION array, dimension (M-1) Contains the subdiagonal entries of the bidiagonal matrix. On exit, E has been destroyed.
U is DOUBLE PRECISION array, dimension at least (LDQ, N) On exit, U contains the left singular vectors.
LDU is INTEGER On entry, leading dimension of U.
VT is DOUBLE PRECISION array, dimension at least (LDVT, M) On exit, VT**T contains the right singular vectors.
LDVT is INTEGER On entry, leading dimension of VT.
SMLSIZ is INTEGER On entry, maximum size of the subproblems at the bottom of the computation tree.
IWORK is INTEGER work array. Dimension must be at least (8 * N)
WORK is DOUBLE PRECISION work array. Dimension must be at least (3 * M**2 + 2 * M)
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
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
November 2011
Contributors:
Ming Gu and Huan Ren, Computer Science
Division, University of California at Berkeley, USA
Author¶
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