Contents

# p?lanhs

Returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value of any element, of an upper Hessenberg matrix.

## Syntax

Include Files
• mkl_scalapack.h
Description
The
p?lanhs
function
returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of an upper Hessenberg distributed matrix
sub(
A
) =
A
(
ia:ia+m-1
,
ja:ja+n-1
)
.
Input Parameters
norm
Specifies the value to be returned by the
function
:
=
'M'
or
'm':
val
=
max
(
abs
(
A
ij
))
, largest absolute value of the matrix
A
.
=
'1'
or
'O'
or
'o':
val
=
norm1
(
A
)
, 1-norm of the matrix
A
(maximum column sum),
=
'I'
or
'i':
val
=
normI
(
A
)
, infinity norm of the matrix
A
(maximum row sum),
=
'F'
,
'f'
,
'E'
or
'e':
val
=
normF
(
A
)
, Frobenius norm of the matrix
A
(square root of sum of squares).
n
(global)
The number of columns in the distributed matrix sub(
A
). When
n
= 0,
p?lanhs
is set to zero.
n
0.
a
(local).
Pointer into the local memory to an array of size
lld_a
*
LOCc
(
ja
+
n
-1)
containing the local pieces of the distributed matrix sub(
A
).
ia
,
ja
(global)
The row and column indices in the global matrix
A
indicating the first row and the first column of the matrix sub(
A
), respectively.
desca
(global and local) array of size
dlen_
. The array descriptor for the distributed matrix A.
work
(local).
Array of size
lwork
.
lwork
0 if
norm
=
'M'
or
'm'
(not referenced),
nq
0 if
norm
= '1',
'O'
or
'o'
,
mp
0 if
norm
=
'I'
or
'i'
,
0 if
norm
=
'F'
,
'f'
,
'E'
or
'e'
(not referenced),
where
iroffa
=
mod
(
ia
-1,
mb_a
),
icoffa
=
mod
(
ja
-1,
nb_a
),
iarow
=
indxg2p
(
ia
,
mb_a
,
myrow
,
rsrc_a
,
nprow
),
iacol
=
indxg2p
(
ja
,
nb_a
,
mycol
,
csrc_a
,
npcol
),
mp
0 =
numroc
(
m
+
iroffa
,
mb_a
,
myrow
,
iarow
,
nprow
),
nq
0 =
numroc
(
n
+
icoffa
,
nb_a
,
mycol
,
iacol
,
npcol
),
indxg2p
and
numroc
are ScaLAPACK tool
functions
;
myrow
,
imycol
,
nprow
, and
npcol
can be determined by calling the
function
blacs_gridinfo
.
Output Parameters
val
The value returned by the function.

#### Product and Performance Information

1

Intel's compilers may or may not optimize to the same degree for non-Intel microprocessors for optimizations that are not unique to Intel microprocessors. These optimizations include SSE2, SSE3, and SSSE3 instruction sets and other optimizations. Intel does not guarantee the availability, functionality, or effectiveness of any optimization on microprocessors not manufactured by Intel. Microprocessor-dependent optimizations in this product are intended for use with Intel microprocessors. Certain optimizations not specific to Intel microarchitecture are reserved for Intel microprocessors. Please refer to the applicable product User and Reference Guides for more information regarding the specific instruction sets covered by this notice.

Notice revision #20110804