Developer Reference for Intel® oneAPI Math Kernel Library - C

Developer Reference

  • 2021.1
  • 12/04/2020
  • Public Content
Contents

p?potrs

Solves a system of linear equations with a Cholesky-factored symmetric/Hermitian distributed positive-definite matrix.

Syntax

void
pspotrs
(
char
*uplo
,
MKL_INT
*n
,
MKL_INT
*nrhs
,
float
*a
,
MKL_INT
*ia
,
MKL_INT
*ja
,
MKL_INT
*desca
,
float
*b
,
MKL_INT
*ib
,
MKL_INT
*jb
,
MKL_INT
*descb
,
MKL_INT
*info
);
void
pdpotrs
(
char
*uplo
,
MKL_INT
*n
,
MKL_INT
*nrhs
,
double
*a
,
MKL_INT
*ia
,
MKL_INT
*ja
,
MKL_INT
*desca
,
double
*b
,
MKL_INT
*ib
,
MKL_INT
*jb
,
MKL_INT
*descb
,
MKL_INT
*info
);
void
pcpotrs
(
char
*uplo
,
MKL_INT
*n
,
MKL_INT
*nrhs
,
MKL_Complex8
*a
,
MKL_INT
*ia
,
MKL_INT
*ja
,
MKL_INT
*desca
,
MKL_Complex8
*b
,
MKL_INT
*ib
,
MKL_INT
*jb
,
MKL_INT
*descb
,
MKL_INT
*info
);
void
pzpotrs
(
char
*uplo
,
MKL_INT
*n
,
MKL_INT
*nrhs
,
MKL_Complex16
*a
,
MKL_INT
*ia
,
MKL_INT
*ja
,
MKL_INT
*desca
,
MKL_Complex16
*b
,
MKL_INT
*ib
,
MKL_INT
*jb
,
MKL_INT
*descb
,
MKL_INT
*info
);
Include Files
  • mkl_scalapack.h
Description
The
p?potrs
function
solves for
X
 a system of distributed linear equations in the form:
sub(
A
)*
X
 = sub(
B
) ,
where sub(
A
) =
A
(
ia
:
ia
+
n
-1,
ja
:
ja
+
n
-1) is an
n
-by-
n
 real symmetric or complex Hermitian positive definite distributed matrix, and sub(
B
) denotes the distributed matrix
B
(
ib
:
ib
+
n
-1,
jb
:
jb
+
nrhs
-1).
This
function
uses Cholesky factorization
sub(
A
) =
U
H
*U
, or sub(
A
) =
L*L
H
computed by
p?potrf
.
Input Parameters
uplo
(global) Must be
'U'
 or
'L'
.
If
uplo
 =
'U'
, upper triangle of sub(
A
) is stored;
If
uplo
 =
'L'
, lower triangle of sub(
A
) is stored.
n
(global) The order of the distributed matrix sub(
A
)
(
n
≥
0)
.
nrhs
(global) The number of right hand sides; the number of columns of the distributed matrix sub(
B
)
(
nrhs
≥
0)
.
a
,
b
(local)
Pointers into the local memory to arrays of local sizes
lld_a
*
LOCc
(
ja
+
n
-1)
 and
lld_b
*
LOCc
(
jb
+
nrhs
-1
)
, respectively.
The array
a
 contains the factors
L
 or
U
 from the Cholesky factorization sub(
A
) =
L
*
L
H
 or sub(
A
) =
U
H
*U
, as computed by
p?potrf
.
On entry, the array
b
 contains the local pieces of the right hand sides sub(
B
).
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
.
ib
,
jb
(global) The row and column indices in the global matrix
B
 indicating the first row and the first column of the matrix sub(
B
), respectively.
descb
(local) array of size
dlen_
. The array descriptor for the distributed matrix
B
.
Output Parameters
b
Overwritten by the local pieces of the solution matrix
X
.
info
If
info
=0
, the execution is successful.
info
 < 0
: if the
i
-th argument is an array and the
j-
th entry
, indexed
j
 - 1,
 had an illegal value, then
info
 = -(
i
*100+
j
); if the
i-
th argument is a scalar and had an illegal value, then
info
 =
-i
.

Product and Performance Information

1

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