Contents

# ?tftri

Computes the inverse of a triangular matrix stored in the Rectangular Full Packed (RFP) format.

## Syntax

Include Files
• mkl.h
Description
Computes the inverse of a triangular matrix
A
stored in the Rectangular Full Packed (RFP) format. For the description of the RFP format, see Matrix Storage Schemes.
This is the block version of the algorithm, calling Level 3 BLAS.
Input Parameters
matrix_layout
Specifies whether matrix storage layout is row major (
LAPACK_ROW_MAJOR
) or column major (
LAPACK_COL_MAJOR
).
transr
Must be
'N'
,
'T'
(for real data) or
'C'
(for complex data).
If
transr
=
'N'
, the Normal
transr
of RFP
A
is stored.
If
transr
=
'T'
, the Transpose
transr
of RFP
A
is stored.
If
transr
=
'C'
, the Conjugate-Transpose
transr
of RFP
A
is stored.
uplo
Must be
'U'
or
'L'
.
Indicates whether the upper or lower triangular part of RFP
A
is stored:
If
uplo
=
'U'
, the array
a
stores the upper triangular part of the matrix
A
.
If
uplo
=
'L'
, the array
a
stores the lower triangular part of the matrix
A
.
diag
Must be
'N'
or
'U'
.
If
diag
=
'N'
, then
A
is not a unit triangular matrix.
If
diag
=
'U'
,
A
is unit triangular: diagonal elements of
A
are assumed to be 1 and not referenced in the array
a
.
n
The order of the matrix
A
;
n
0.
a
Array, size max(1,
n
*(
n
+ 1)/2). The array
a
contains the matrix
A
in the RFP format.
Output Parameters
a
The (triangular) inverse of the original matrix in the same storage format.
Return Values
This function returns a value
info
.
If
info
=0
, the execution is successful.
If
info
=
-i
, parameter
i
If
info
=
i
,
A
i
,
i
is exactly zero. The triangular matrix is singular and its inverse cannot be computed.

#### 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