Developer Reference

  • 2020.2
  • 07/15/2020
  • Public Content
Contents

?pptrf

Computes the Cholesky factorization of a symmetric (Hermitian) positive-definite matrix using packed storage.

Syntax

call spptrf
(
uplo
,
n
,
ap
,
info
)
call dpptrf
(
uplo
,
n
,
ap
,
info
)
call cpptrf
(
uplo
,
n
,
ap
,
info
)
call zpptrf
(
uplo
,
n
,
ap
,
info
)
call pptrf
(
ap
[
,
uplo
]
[
,
info
]
)
Include Files
  • mkl.fi
    ,
    lapack.f90
Description
The routine forms the Cholesky factorization of a symmetric positive-definite or, for complex data, Hermitian positive-definite packed matrix
A
:
A
=
U
T
*U
for real data,
A
=
U
H
*U
for complex data
if
uplo
=
'U'
A
=
L*L
T
for real data,
A
=
L*L
H
for complex data
if
uplo
=
'L'
where
L
is a lower triangular matrix and
U
is upper triangular.
This routine supports the Progress Routine feature. See Progress Function for details.
Input Parameters
uplo
CHARACTER*1
.
Must be
'U'
or
'L'
.
Indicates whether the upper or lower triangular part of
A
is packed in the array
ap
, and how
A
is factored:
If
uplo
=
'U'
, the array
ap
stores the upper triangular part of the matrix
A
, and
A
is factored as
U
H
*U
.
If
uplo
=
'L'
, the array
ap
stores the lower triangular part of the matrix
A
;
A
is factored as
L*L
H
.
n
INTEGER
.
The order of matrix
A
;
n
0.
ap
REAL
for
spptrf
DOUBLE PRECISION
for
dpptrf
COMPLEX
for
cpptrf
DOUBLE COMPLEX
for
zpptrf
.
Array, size at least max(1,
n
(
n
+1)/2). The array
ap
contains either the upper or the lower triangular part of the matrix
A
(as specified by
uplo
) in packed storage (see Matrix Storage Schemes).
Output Parameters
ap
Overwritten by the Cholesky factor
U
or
L
, as specified by
uplo
.
info
INTEGER
.
If
info
=0
, the execution is successful.
If
info
=
-i
, the
i-
th parameter 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
.
LAPACK 95 Interface Notes
Routines in Fortran 95 interface have fewer arguments in the calling sequence than their FORTRAN 77 counterparts. For general conventions applied to skip redundant or reconstructible arguments, see LAPACK 95 Interface Conventions.
Specific details for