Developer Reference

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

?laqps

Computes a step of QR factorization with column pivoting of a real
m
-by-
n
matrix A by using BLAS level 3.

Syntax

call slaqps
(
m
,
n
,
offset
,
nb
,
kb
,
a
,
lda
,
jpvt
,
tau
,
vn1
,
vn2
,
auxv
,
f
,
ldf
)
call dlaqps
(
m
,
n
,
offset
,
nb
,
kb
,
a
,
lda
,
jpvt
,
tau
,
vn1
,
vn2
,
auxv
,
f
,
ldf
)
call claqps
(
m
,
n
,
offset
,
nb
,
kb
,
a
,
lda
,
jpvt
,
tau
,
vn1
,
vn2
,
auxv
,
f
,
ldf
)
call zlaqps
(
m
,
n
,
offset
,
nb
,
kb
,
a
,
lda
,
jpvt
,
tau
,
vn1
,
vn2
,
auxv
,
f
,
ldf
)
Include Files
  • mkl.fi
Description
The routine computes a step of
QR
factorization with column pivoting of a real
m
-by-
n
matrix
A
by using BLAS level 3. The routine tries to factorize
NB
columns from
A
starting from the row
offset
+1, and updates all of the matrix with BLAS level 3 routine
?gemm
.
In some cases, due to catastrophic cancellations,
?laqps
cannot factorize
NB
columns. Hence, the actual number of factorized columns is returned in
kb
.
Block
A
(1:
offset
,1:
n
)
is accordingly pivoted, but not factorized.
Input Parameters
m
INTEGER
. The number of rows of the matrix
A
.
m
0
.
n
INTEGER
. The number of columns of the matrix
A
.
n
0
.
offset
INTEGER
. The number of rows of
A
that have been factorized in previous steps.
nb
INTEGER
. The number of columns to factorize.
a
REAL
for
slaqps
DOUBLE PRECISION
for
dlaqps
COMPLEX
for
claqps
DOUBLE COMPLEX
for
zlaqps
Array,
DIMENSION
(
lda
,
n
).
On entry, the
m
-by-
n
matrix
A
.
lda
INTEGER
. The leading dimension of the array
a
.
lda