public interface bdsdc
BDSDC computes the singular value decomposition (SVD) of a real
N-by-N (upper or lower) bidiagonal matrix B: B = U * S * VT,
using a divide and conquer method, where S is a diagonal matrix
with non-negative diagonal elements (the singular values of B), and
U and VT are orthogonal matrices of left and right singular vectors,
respectively. BDSDC can be used to compute all singular values,
and optionally, singular vectors or singular vectors in compact form.
This code makes very mild assumptions about floating point
arithmetic. It will work on machines with a guard digit in
add/subtract, or on those binary machines without guard digits
which subtract like the Cray X-MP, Cray Y-MP, Cray C-90, or Cray-2.
It could conceivably fail on hexadecimal or decimal machines
without guard digits, but we know of none. See DLASD3 for details.
The code currently calls DLASDQ if singular values only are desired.
However, it can be slightly modified to compute singular values
using the divide and conquer method.
Subroutines
Arguments
| Type |
Intent | Optional | Attributes |
|
Name |
|
|
character(len=1),
|
intent(in) |
|
|
:: |
uplo |
|
|
character(len=1),
|
intent(in) |
|
|
:: |
compq |
|
|
integer(kind=ilp),
|
intent(in) |
|
|
:: |
n |
|
|
real(kind=dp),
|
intent(inout) |
|
|
:: |
d(*) |
|
|
real(kind=dp),
|
intent(inout) |
|
|
:: |
e(*) |
|
|
real(kind=dp),
|
intent(out) |
|
|
:: |
u(ldu,*) |
|
|
integer(kind=ilp),
|
intent(in) |
|
|
:: |
ldu |
|
|
real(kind=dp),
|
intent(out) |
|
|
:: |
vt(ldvt,*) |
|
|
integer(kind=ilp),
|
intent(in) |
|
|
:: |
ldvt |
|
|
real(kind=dp),
|
intent(out) |
|
|
:: |
q(*) |
|
|
integer(kind=ilp),
|
intent(out) |
|
|
:: |
iq(*) |
|
|
real(kind=dp),
|
intent(out) |
|
|
:: |
work(*) |
|
|
integer(kind=ilp),
|
intent(out) |
|
|
:: |
iwork(*) |
|
|
integer(kind=ilp),
|
intent(out) |
|
|
:: |
info |
|
Arguments
| Type |
Intent | Optional | Attributes |
|
Name |
|
|
character(len=1),
|
intent(in) |
|
|
:: |
uplo |
|
|
character(len=1),
|
intent(in) |
|
|
:: |
compq |
|
|
integer(kind=ilp),
|
intent(in) |
|
|
:: |
n |
|
|
real(kind=sp),
|
intent(inout) |
|
|
:: |
d(*) |
|
|
real(kind=sp),
|
intent(inout) |
|
|
:: |
e(*) |
|
|
real(kind=sp),
|
intent(out) |
|
|
:: |
u(ldu,*) |
|
|
integer(kind=ilp),
|
intent(in) |
|
|
:: |
ldu |
|
|
real(kind=sp),
|
intent(out) |
|
|
:: |
vt(ldvt,*) |
|
|
integer(kind=ilp),
|
intent(in) |
|
|
:: |
ldvt |
|
|
real(kind=sp),
|
intent(out) |
|
|
:: |
q(*) |
|
|
integer(kind=ilp),
|
intent(out) |
|
|
:: |
iq(*) |
|
|
real(kind=sp),
|
intent(out) |
|
|
:: |
work(*) |
|
|
integer(kind=ilp),
|
intent(out) |
|
|
:: |
iwork(*) |
|
|
integer(kind=ilp),
|
intent(out) |
|
|
:: |
info |
|
Module Procedures
