Contents

# mkl_?potrf_compact

Computes the Cholesky factorization of a set of symmetric (Hermitian), positive-definite matrices, stored in Compact format (see Compact Format for details).

## Syntax

Description
The routine forms the Cholesky factorization of a set of symmetric, positive definite (or, for complex data, Hermitian, positive-definite),
n
x
n
matrices A
c
, stored in Compact format, as:
• A
c
= U
c
T
*U
c
(for real data), A
c
= U
c
H
*U
c
(for complex data), if uplo = MKL_UPPER
• A
c
= L
c
*L
c
T
(for real data), A
c
= L
c
*L
c
H
(for complex data), if uplo = MKL_LOWER
where L
c
is a lower triangular matrix, and U
c
is upper triangular. The factorization (output) data will also be stored in Compact format.
Before calling this routine, call
mkl_?gepack_compact
to store the matrices in the Compact format.
Compact routines have some limitations; see Numerical Limitations.
Input Parameters
layout
Specifies whether two-dimensional array storage is row-major (
MKL_ROW_MAJOR
) or column-major (
MKL_COL_MAJOR
).
uplo
Must be
MKL_UPPER
or
MKL_LOWER
Indicates whether the upper or lower triangular part of A
c
has been stored and will be factored.
If uplo = MKL_UPPER, the upper triangular part of A
c
is stored, and the strictly lower triangular part of A
c
is not referenced.
If uplo = MKL_LOWER, the lower triangular part of A
c
is stored, and the strictly upper triangular part of A
c
is not referenced.
n
The order of A
c
; n >= 0.
ldap
Column stride (column-major layout) or row stride (row-major layout) of A
c
.
ap
Points to the beginning of the
nm
A
c
matrices. On entry,
ap
contains either the upper or the lower triangular part of A
c
(see uplo).
format
Specifies the format of the compact matrices. See Compact Format or mkl_get_format_compact for details.
nm
Total number of matrices stored in Compact format;
nm
>= 0.
Application Notes:
Before calling this routine,
mkl_?gepack_compact
must be called. After calling this routine,
mkl_?geunpack_compact
should be called, unless another compact routine will be called for the Compact format matrices.
The total number of floating-point operations is approximately
nm
* (1/3)
n
3
for real flavors and
nm
* (4/3)
n
3
for complex flavors.
Output Parameters
ap
The upper or lower triangular part of A
c
, stored in Compact format in
ap
, is overwritten by its Cholesky factor U
c
or L
c
(as specified by uplo).
ap
now points to the beginning of this set of factors, stored in Compact format.
info
The parameter is not currently used in this routine. It is reserved for the future use.

#### Product and Performance Information

1

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