## Developer Reference

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

# ?la_porpvgrw

Computes the reciprocal pivot growth factor
norm(A)/norm(U)
for a symmetric or Hermitian positive-definite matrix.

## Syntax

Include Files
• mkl.fi
Description
The
?la_porpvgrw
routine computes the reciprocal pivot growth factor
norm(
A
)/norm(
U
)
. The max absolute element norm is used. If this is much less than 1, the stability of the
LU
factorization of the equilibrated matrix
A
could be poor. This also means that the solution
X
, estimated condition numbers, and error bounds could be unreliable.
Input Parameters
uplo
CHARACTER*1
. Must be
'U'
or
'L'
.
Specifies the triangle of A to store:
If
uplo
=
'U'
, the upper triangle of
A
is stored,
If
uplo
=
'L'
, the lower triangle of
A
is stored.
ncols
INTEGER
. The number of columns of the matrix
A
;
ncols
0.
a
,
af
REAL
for
sla_porpvgrw
DOUBLE PRECISION
for
dla_porpvgrw
COMPLEX
for
cla_porpvgrw
DOUBLE COMPLEX
for
zla_porpvgrw
.
Arrays:
a
(
lda
,*)
,
af
(
ldaf
,*)
.
The array
a
contains the input
n
-by-
n
matrix
A
. The second dimension of
a
must be at least
max(1,
n
)
.
The array
af
contains the triangular factor
L
or
U
from the Cholesky factorization as computed by
?potrf
:
A = U
T
*U
or
A = L*L
T
for real flavors,
A = U
H
*U
or
A = L*L
H
for complex flavors.
The second dimension of
af
must be at least
max(1,
n
)
.
lda
INTEGER
a
;
lda
max(1,
n
)
.
ldaf
INTEGER
af
;
ldaf
max(1,
n
)
.
work
REAL
for
sla_porpvgrw
and
cla_porpvgrw
DOUBLE PRECISION
for
dla_porpvgrw
and
zla_porpvgrw
.
Workspace array, dimension 2*
n
.

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