Developer Reference

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

?pftrs

Solves a system of linear equations with a Cholesky-factored symmetric (Hermitian) positive-definite coefficient matrix using the Rectangular Full Packed (RFP) format.

Syntax

call spftrs
(
transr
,
uplo
,
n
,
nrhs
,
a
,
b
,
ldb
,
info
)
call dpftrs
(
transr
,
uplo
,
n
,
nrhs
,
a
,
b
,
ldb
,
info
)
call cpftrs
(
transr
,
uplo
,
n
,
nrhs
,
a
,
b
,
ldb
,
info
)
call zpftrs
(
transr
,
uplo
,
n
,
nrhs
,
a
,
b
,
ldb
,
info
)
Include Files
  • mkl.fi
    ,
    lapack.f90
Description
The routine solves a system of linear equations
A*X
=
B
with a symmetric positive-definite or, for complex data, Hermitian positive-definite matrix
A
using the Cholesky factorization of
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'
Before calling
?pftrs
, you must call
?pftrf
to compute the Cholesky factorization of
A
.
L
stands for a lower triangular matrix and
U
for an upper triangular matrix.
The matrix
A
is in the Rectangular Full Packed (RFP) format. For the description of the RFP format, see Matrix Storage Schemes .
Input Parameters
transr
CHARACTER*1
.
Must be
'N'
,
'T'
(for real data) or
'C'
(for complex data).
If
transr
=
'N'
, the untransposed factor of
A
is stored in RFP format.
If
transr
=
'T'
, the transposed factor of
A
is stored in RFP format.
If
transr
=
'C'
, the conjugate-transposed factor of
A
is stored in RFP format.
uplo
CHARACTER*1
.
Must be
'U'
or
'L'
.
Indicates how the input matrix
A
has been factored:
If
uplo
=
'U'
,
U
is stored, where
A
=
U
T
*
U
for real data,
A
=
U
H
*
U
for complex data.
If
uplo
=