Contents

# p?trti2

Computes the inverse of a triangular matrix (local unblocked algorithm).

## Syntax

Include Files
• mkl_scalapack.h
Description
The
p?trti2
function
computes the inverse of a real/complex upper or lower triangular block matrix sub
(
A
) =
A
(
ia
:
ia
+
n
-1
,
ja
:
ja
+
n
-1)
.
This matrix should be contained in one and only one process memory space (local operation).
Input Parameters
uplo
(global)
Specifies whether the matrix sub (
A
) is upper or lower triangular.
=
'U'
: sub (
A
) is upper triangular
=
'L'
: sub (
A
) is lower triangular.
diag
(global)
Specifies whether or not the matrix
A
is unit triangular.
=
'N'
: sub (
A
) is non-unit triangular
=
'U'
: sub (
A
) is unit triangular.
n
(global)
The number of rows and columns to be operated on, i.e., the order of the distributed submatrix
sub(
A
)
.
n
0
.
a
(local)
Pointer into the local memory to an array,
size
lld_a
*
LOCc
(
ja
+
n
-1)
.
On entry, this array contains the local pieces of the triangular matrix sub(
A
).
If
uplo
=
'U'
n
-by-
n
upper triangular part of the matrix sub(
A
) contains the upper triangular part of the matrix, and the strictly lower triangular part of sub(
A
) is not referenced.
If
uplo
=
'L'
n
-by-
n
lower triangular part of the matrix sub(
A
) contains the lower triangular part of the matrix, and the strictly upper triangular part of sub(
A
) is not referenced. If
diag
=
'U'
, the diagonal elements of sub(
A
) are not referenced either and are assumed to be 1.
ia
,
ja
(global)
The row and column indices in the global matrix
A
indicating the first row and the first column of the sub(
A
), respectively.
desca
(global and local) array of size
dlen_
. The array descriptor for the distributed matrix
A
.
Output Parameters
a
On exit, the (triangular) inverse of the original matrix, in the same storage format.
info
= 0
: successful exit
< 0
: if the
i
-th argument is an array and the
j
-th entry
, indexed
j
-1,
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

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