 |
LAPACK 3.12.0
LAPACK: Linear Algebra PACKage
|
|
LAPACK 3.12.0
LAPACK: Linear Algebra PACKage
|
| subroutine slasd0 | ( | integer | n, |
| integer | sqre, | ||
| real, dimension( * ) | d, | ||
| real, dimension( * ) | e, | ||
| real, dimension( ldu, * ) | u, | ||
| integer | ldu, | ||
| real, dimension( ldvt, * ) | vt, | ||
| integer | ldvt, | ||
| integer | smlsiz, | ||
| integer, dimension( * ) | iwork, | ||
| real, dimension( * ) | work, | ||
| integer | info | ||
| ) |
SLASD0 computes the singular values of a real upper bidiagonal n-by-m matrix B with diagonal d and off-diagonal e. Used by sbdsdc.
Download SLASD0 + dependencies [TGZ] [ZIP] [TXT]
Using a divide and conquer approach, SLASD0 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, SLASDA, computes only the singular values, and optionally, the singular vectors in compact form.
| [in] | 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. |
| [in] | 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; |
| [in,out] | D | D 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. |
| [in,out] | E | E is REAL array, dimension (M-1)
Contains the subdiagonal entries of the bidiagonal matrix.
On exit, E has been destroyed. |
| [in,out] | U | U is REAL array, dimension (LDU, N)
On exit, U contains the left singular vectors,
if U passed in as (N, N) Identity. |
| [in] | LDU | LDU is INTEGER
On entry, leading dimension of U. |
| [in,out] | VT | VT is REAL array, dimension (LDVT, M)
On exit, VT**T contains the right singular vectors,
if VT passed in as (M, M) Identity. |
| [in] | LDVT | LDVT is INTEGER
On entry, leading dimension of VT. |
| [in] | SMLSIZ | SMLSIZ is INTEGER
On entry, maximum size of the subproblems at the
bottom of the computation tree. |
| [out] | IWORK | IWORK is INTEGER array, dimension (8*N) |
| [out] | WORK | WORK is REAL array, dimension (3*M**2+2*M) |
| [out] | 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 |
1.9.8