Developer Reference

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

?tptri

Computes the inverse of a triangular matrix using packed storage.

Syntax

call stptri
(
uplo
,
diag
,
n
,
ap
,
info
)
call dtptri
(
uplo
,
diag
,
n
,
ap
,
info
)
call ctptri
(
uplo
,
diag
,
n
,
ap
,
info
)
call ztptri
(
uplo
,
diag
,
n
,
ap
,
info
)
call tptri
(
ap
[
,
uplo
]
[
,
diag
]
[
,
info
]
)
Include Files
  • mkl.fi
    ,
    lapack.f90
Description
The routine computes the inverse
inv(
A
)
of a packed triangular matrix
A
.
Input Parameters
uplo
CHARACTER*1
.
Must be
'U'
or
'L'
.
Indicates whether
A
is upper or lower triangular:
If
uplo
=
'U'
, then
A
is upper triangular.
If
uplo
=
'L'
, then
A
is lower triangular.
diag
CHARACTER*1
.
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
ap
.
n
INTEGER
.
The order of the matrix
A
;
n
0
.
ap
REAL
for
stptri
DOUBLE PRECISION
for
dtptri
COMPLEX
for
ctptri
DOUBLE COMPLEX
for
ztptri
.
Array, size at least
max(1,
n
(
n
+1)/2)
.
Contains the packed triangular matrix A.
Output Parameters
ap
Overwritten by the packed
n
-by-
n
matrix
inv(
A
)
.
info
INTEGER
.
If
info
= 0
, the execution is successful.
If
info
=
-i
, the
i
-th parameter had an illegal value.
If
info
=
i
, the
i
-th diagonal element of
A
is zero,
A
is singular, and the inversion could not be completed.
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 .