Contents

# ?hetri2x

Computes the inverse of a Hermitian indefinite matrix after
?hetri2
allocates memory
.

## Syntax

Include Files
• mkl.h
Description
The routine computes the inverse
inv(
A
)
of a Hermitian indefinite matrix
A
using the factorization
A
=
U*D*U
H
or
A
=
L*D*L
H
computed by
?hetrf
.
The
?hetri2x
actually computes the inverse after the
?hetri2
routine
allocates memory
before calling
?hetri2x
.
Input Parameters
matrix_layout
Specifies whether matrix storage layout is row major (
LAPACK_ROW_MAJOR
) or column major (
LAPACK_COL_MAJOR
).
uplo
Must be
'U'
or
'L'
.
Indicates how the input matrix
A
has been factored:
If
uplo
=
'U'
, the array
a
stores the factorization
A
=
U*D*U
H
.
If
uplo
=
'L'
, the array
a
stores the factorization
A
=
L*D*L
H
.
n
The order of the matrix
A
;
n
0
.
a
Arrays
a
(size max(1,
lda
*
n
))
contains the
nb
(block size) diagonal matrix
D
and the multipliers used to obtain the factor
U
or
L
as returned by
?hetrf
.
lda
a
;
lda
max(1,
n
)
.
ipiv
Array, size at least
max(1,
n
)
.
Details of the interchanges and the
nb
structure of
D
as returned by
?hetrf
.
nb
Block size.
Output Parameters
a
If
info
= 0, the symmetric inverse of the original matrix.
If
info
=
'U'
, the upper triangular part of the inverse is formed and the part of
A
below the diagonal is not referenced.
If
info
=
'L'
, the lower triangular part of the inverse is formed and the part of
A
above the diagonal is not referenced.
Return Values
This function returns a value
info
.
If
info
= 0, the execution is successful.
If
info
=
-i
, parameter
i
If
info
=
i
,
D
i
i
= 0;
D
is singular and its inversion could not be computed.

#### Product and Performance Information

1

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