Developer Reference for Intel® oneAPI Math Kernel Library - C

Developer Reference

Contents

p?lansy
,
p?lanhe

Returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value of any element, of a real symmetric or a complex Hermitian matrix.

Syntax

float
pslansy
(
char
*norm
,
char
*uplo
,
MKL_INT
*n
,
float
*a
,
MKL_INT
*ia
,
MKL_INT
*ja
,
MKL_INT
*desca
,
float
*work
);
double
pdlansy
(
char
*norm
,
char
*uplo
,
MKL_INT
*n
,
double
*a
,
MKL_INT
*ia
,
MKL_INT
*ja
,
MKL_INT
*desca
,
double
*work
);
float
pclansy
(
char
*norm
,
char
*uplo
,
MKL_INT
*n
,
MKL_Complex8
*a
,
MKL_INT
*ia
,
MKL_INT
*ja
,
MKL_INT
*desca
,
float
*work
);
double
pzlansy
(
char
*norm
,
char
*uplo
,
MKL_INT
*n
,
MKL_Complex16
*a
,
MKL_INT
*ia
,
MKL_INT
*ja
,
MKL_INT
*desca
,
double
*work
);
float
pclanhe
(
char
*norm
,
char
*uplo
,
MKL_INT
*n
,
MKL_Complex8
*a
,
MKL_INT
*ia
,
MKL_INT
*ja
,
MKL_INT
*desca
,
float
*work
);
double
pzlanhe
(
char
*norm
,
char
*uplo
,
MKL_INT
*n
,
MKL_Complex16
*a
,
MKL_INT
*ia
,
MKL_INT
*ja
,
MKL_INT
*desca
,
double
*work
);
Include Files
  • mkl_scalapack.h
Description
The
p?lansy
 and
p?lanhe
functions
return the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a distributed matrix
sub(
A
) =
A
(
ia
:
ia
+
m
-1
,
ja
:
ja
+
n
-1)
.
Input Parameters
norm
(global) Specifies what value is returned by the
function
:
=
'M'
 or
'm':
val
 =
max
(
abs
(
A
ij
))
, largest absolute value of the matrix
A
, it s not a matrix norm.
=
'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).
uplo
(global) Specifies whether the upper or lower triangular part of the symmetric matrix sub(
A
) is to be referenced.
=
'U'
: Upper triangular part of sub(
A
) is referenced,
=
'L'
: Lower triangular part of sub(
A
) is referenced.
n
(global)
The number of columns in the distributed matrix sub(
A
). When
n
 = 0
,
p?lansy
 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
).
If
uplo
 =
'U'
, the leading
n
-by-
n
 upper triangular part of sub(
A
) contains the upper triangular matrix whose norm is to be computed, and the strictly lower triangular part of this matrix is not referenced. If
uplo
 =
'L'
, the leading
n
-by-
n
 lower triangular part of sub(
A
) contains the lower triangular matrix whose norm is to be computed, and the strictly upper triangular part of sub(
A
) is not referenced.
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),
2*
nq
0+
mp
0+
ldw
 if
norm
 = '1',
'O'
 or
'o'
,
'I'
 or
'i'
,
where
ldw
 is given by:
if(
nprow
≠
npcol
 ) then
ldw
 =
mb_a
*iceil(iceil(
np
0,
mb_a
),(
lcm
/
nprow
))
else
ldw
 = 0
end if
0 if
norm
 =
'F'
,
'f'
,
'E'
 or
'e'
 (not referenced),
where
lcm
 is the least common multiple of
nprow
 and
npcol
,
lcm
 = ilcm(
nprow
,
npcol
 )
 and
iceil
(
x
,
y
)
 is a ScaLAPACK function that returns ceiling
(
x
/
y
)
.
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
),
ilcm
,
iceil
,
indxg2p
, and
numroc
 are ScaLAPACK tool functions;
myrow
,
mycol
,
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

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.