Developer Reference

  • 2020.2
  • 07/15/2020
  • Public Content
Contents

?lasd7

Merges the two sets of singular values together into a single sorted set. Then it tries to deflate the size of the problem. Used by
?bdsdc
.

Syntax

call slasd7
(
icompq
,
nl
,
nr
,
sqre
,
k
,
d
,
z
,
zw
,
vf
,
vfw
,
vl
,
vlw
,
alpha
,
beta
,
dsigma
,
idx
,
idxp
,
idxq
,
perm
,
givptr
,
givcol
,
ldgcol
,
givnum
,
ldgnum
,
c
,
s
,
info
)
call dlasd7
(
icompq
,
nl
,
nr
,
sqre
,
k
,
d
,
z
,
zw
,
vf
,
vfw
,
vl
,
vlw
,
alpha
,
beta
,
dsigma
,
idx
,
idxp
,
idxq
,
perm
,
givptr
,
givcol
,
ldgcol
,
givnum
,
ldgnum
,
c
,
s
,
info
)
Include Files
  • mkl.fi
Description
The routine
?lasd7
merges the two sets of singular values together into a single sorted set. Then it tries to deflate the size of the problem. There are two ways in which deflation can occur: when two or more singular values are close together or if there is a tiny entry in the
Z
vector. For each such occurrence the order of the related secular equation problem is reduced by one.
?lasd7
is called from
?lasd6
.
Input Parameters
icompq
INTEGER
.
Specifies whether singular vectors are to be computed in compact form, as follows:
= 0: Compute singular values only.
= 1: Compute singular vectors of upper bidiagonal matrix in compact form.
nl
INTEGER
.
The row dimension of the upper block.
nl
1
.
nr
INTEGER
.
The row dimension of the lower block.
nr
1
.
sqre
INTEGER
.
= 0: the lower block is an
nr
-by-
nr
square matrix.
= 1: the lower block is an
nr
-by-(
nr
+1) rectangular matrix. The bidiagonal matrix has
n
=
nl
+
nr
+ 1
rows and
m
=
n
+
sqre
n
columns.
d
REAL
for
slasd7
.
DOUBLE PRECISION
for
dlasd7
.
Array,
DIMENSION
(
n
). On entry
d
contains the singular values of the two submatrices to be combined.
zw
REAL
for
slasd7
.
DOUBLE PRECISION
for
dlasd7
.
Array,
DIMENSION
(
m
).
Workspace for
z
.
vf
REAL
for
slasd7
.
DOUBLE PRECISION
for
dlasd7
.
Array,
DIMENSION
(
m
). On entry,
vf
(1:
nl
+1)
contains the first components of all right singular vectors of the upper block; and
vf
(
nl
+2:
m
)
contains the first components of all right singular vectors of the lower block.
vfw
REAL
for
slasd7
.
DOUBLE PRECISION
for
dlasd7
.
Array,
DIMENSION
(
m
).
Workspace for
vf
.
vl
REAL
for