Developer Reference

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

p?lacon

Estimates the 1-norm of a square matrix, using the reverse communication for evaluating matrix-vector products.

Syntax

call pslacon
(
n
,
v
,
iv
,
jv
,
descv
,
x
,
ix
,
jx
,
descx
,
isgn
,
est
,
kase
)
call pdlacon
(
n
,
v
,
iv
,
jv
,
descv
,
x
,
ix
,
jx
,
descx
,
isgn
,
est
,
kase
)
call pclacon
(
n
,
v
,
iv
,
jv
,
descv
,
x
,
ix
,
jx
,
descx
,
isgn
,
est
,
kase
)
call pzlacon
(
n
,
v
,
iv
,
jv
,
descv
,
x
,
ix
,
jx
,
descx
,
isgn
,
est
,
kase
)
Description
The
p?lacon
routine
estimates the 1-norm of a square, real/unitary distributed matrix
A
. Reverse communication is used for evaluating matrix-vector products.
x
and
v
are aligned with the distributed matrix
A
, this information is implicitly contained within
iv
,
ix
,
descv
, and
descx
.
Input Parameters
n
(global)
INTEGER
.
The length of the distributed vectors
v
and
x. n
0.
v
(local).
REAL
for
pslacon
DOUBLE PRECISION
for
pdlacon
COMPLEX
for
pclacon
COMPLEX*16
for
pzlacon.
Pointer into the local memory to an array of size
LOCr
(
n
+mod(
iv
-1,
mb_v
)). On the final return,
v
=
a
*
w
, where
est
= norm(
v
)/norm(
w
) (
w
is not returned).
iv
,
jv
(global)
INTEGER
.
The row and column indices in the global matrix
V
indicating the first row and the first column of the submatrix
V
, respectively.
descv
(global and local)
INTEGER
array of size
dlen_
. The array descriptor for the distributed matrix V.
x
(local).
REAL
for
pslacon
DOUBLE PRECISION
for
pdlacon
COMPLEX
for
pclacon
COMPLEX*16
for
pzlacon.
Pointer into the local memory to an array of size
LOCr
(
n
+mod(
ix
-1,
mb_x
)).
ix
,
jx
(global)
INTEGER
.
The row and column indices in the global matrix
X
indicating the first row and the first column of the submatrix
X
, respectively.
descx
(global and local)
INTEGER
array of size
dlen_
. The array descriptor for the distributed matrix X.
isgn
(local).
INTEGER
.
Array of size
LOCr
(
n
+mod(
ix
-1,
mb_x
)).
isgn
is aligned with
x
and
v
.
kase
(local).
INTEGER
.
On the initial call to
p?lacon
,
kase
should be 0.
Output Parameters
x
(local).
On an intermediate return, X should be overwritten by
A
*