Contents

# ?pftrf

Computes the Cholesky factorization of a symmetric (Hermitian) positive-definite matrix using the Rectangular Full Packed (RFP) format .

## Syntax

Include Files
• mkl.h
Description
The routine forms the Cholesky factorization of a symmetric positive-definite or, for complex data, a Hermitian positive-definite matrix
A
:
 A = UT*U for real data, A = UH*U for complex data if uplo='U' A = L*LT for real data, A = L*LH for complex data if uplo='L'
where
L
is a lower triangular matrix and
U
is upper triangular.
The matrix
A
is 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
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
.
n
The order of the matrix
A
;
n
0.
a
Array, size
(
n
*(
n
+1)/2)
. The array
a
contains the matrix
A
in the RFP format.
Output Parameters
a
a
is overwritten by the Cholesky factor
U
or
L
, as specified by
uplo
and
trans
.
Return Values
This function returns a value
info
.
If
info
=0
, the execution is successful.
If
info
=
-i
, parameter
i
had an illegal value.
If
info
=
i
, the leading minor of order
i
(and therefore the matrix
A
itself) is not positive-definite, and the factorization could not be completed. This may indicate an error in forming the matrix
A
.

#### Product and Performance Information

1

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