ztftri - compute the inverse of a triangular matrix A stored in RFP format
SUBROUTINE ZTFTRI(TRANSR, UPLO, DIAG, N, A, INFO) CHARACTER*1 TRANSR, UPLO, DIAG INTEGER INFO, N DOUBLE COMPLEX A(0:*) SUBROUTINE ZTFTRI_64(TRANSR, UPLO, DIAG, N, A, INFO) CHARACTER*1 TRANSR, UPLO, DIAG INTEGER*8 INFO, N DOUBLE COMPLEX A(0:*) F95 INTERFACE SUBROUTINE TFTRI(TRANSR, UPLO, DIAG, N, A, INFO) INTEGER :: N, INFO CHARACTER(LEN=1) :: TRANSR, UPLO, DIAG COMPLEX(8), DIMENSION(:) :: A SUBROUTINE TFTRI_64(TRANSR, UPLO, DIAG, N, A, INFO) INTEGER(8) :: N, INFO CHARACTER(LEN=1) :: TRANSR, UPLO, DIAG COMPLEX(8), DIMENSION(:) :: A C INTERFACE #include <sunperf.h> void ztftri (char transr, char uplo, char diag, int n, doublecomplex *a, int *info); void ztftri_64 (char transr, char uplo, char diag, long n, doublecom- plex *a, long *info);
Oracle Solaris Studio Performance Library ztftri(3P)
NAME
ztftri - compute the inverse of a triangular matrix A stored in RFP
format
SYNOPSIS
SUBROUTINE ZTFTRI(TRANSR, UPLO, DIAG, N, A, INFO)
CHARACTER*1 TRANSR, UPLO, DIAG
INTEGER INFO, N
DOUBLE COMPLEX A(0:*)
SUBROUTINE ZTFTRI_64(TRANSR, UPLO, DIAG, N, A, INFO)
CHARACTER*1 TRANSR, UPLO, DIAG
INTEGER*8 INFO, N
DOUBLE COMPLEX A(0:*)
F95 INTERFACE
SUBROUTINE TFTRI(TRANSR, UPLO, DIAG, N, A, INFO)
INTEGER :: N, INFO
CHARACTER(LEN=1) :: TRANSR, UPLO, DIAG
COMPLEX(8), DIMENSION(:) :: A
SUBROUTINE TFTRI_64(TRANSR, UPLO, DIAG, N, A, INFO)
INTEGER(8) :: N, INFO
CHARACTER(LEN=1) :: TRANSR, UPLO, DIAG
COMPLEX(8), DIMENSION(:) :: A
C INTERFACE
#include <sunperf.h>
void ztftri (char transr, char uplo, char diag, int n, doublecomplex
*a, int *info);
void ztftri_64 (char transr, char uplo, char diag, long n, doublecom-
plex *a, long *info);
PURPOSE
ztftri computes the inverse of a triangular matrix A stored in RFP for-
mat.
This is a Level 3 BLAS version of the algorithm.
ARGUMENTS
TRANSR (input)
TRANSR is CHARACTER*1
= 'N': The Normal TRANSR of RFP A is stored;
= 'C': The Conjugate-transpose TRANSR of RFP A is stored.
UPLO (input)
UPLO is CHARACTER*1
= 'U': A is upper triangular;
= 'L': A is lower triangular.
DIAG (input)
DIAG is CHARACTER*1
= 'N': A is non-unit triangular;
= 'U': A is unit triangular.
N (input)
N is INTEGER
The order of the matrix A. N >= 0.
A (input/output)
A is COMPLEX*16 array, dimension ( N*(N+1)/2 );
On entry, the triangular matrix A in RFP format. RFP format
is described by TRANSR, UPLO, and N as follows: If TRANSR =
(0:N-1,0:k) when N is odd; k=N/2. IF TRANSR = 'C' then RFP is
the Conjugate-transpose of RFP A as defined when TRANSR =
'N'. The contents of RFP A are defined by UPLO as follows: If
UPLO = 'U' the RFP A contains the nt elements of upper packed
A; If UPLO = 'L' the RFP A contains the nt elements of lower
packed A. The LDA of RFP A is (N+1)/2 when TRANSR = 'C'. When
TRANSR is 'N' the LDA is N+1 when N is even and N is odd. See
the Note below for more details.
On exit, the (triangular) inverse of the original matrix, in
the same storage format.
INFO (output)
INFO is INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
> 0: if INFO = i, A(i,i) is exactly zero. The triangular
matrix is singular and its inverse can not be computed.
FURTHER DETAILS
We first consider Standard Packed Format when N is even.
We give an example where N = 6.
AP is Upper AP is Lower
00 01 02 03 04 05 00
11 12 13 14 15 10 11
22 23 24 25 20 21 22
33 34 35 30 31 32 33
44 45 40 41 42 43 44
55 50 51 52 53 54 55
Let TRANSR = 'N'. RFP holds AP as follows:
For UPLO = 'U' the upper trapezoid A(0:5,0:2) consists of the last
three columns of AP upper. The lower triangle A(4:6,0:2) consists of
conjugate-transpose of the first three columns of AP upper.
For UPLO = 'L' the lower trapezoid A(1:6,0:2) consists of the first
three columns of AP lower. The upper triangle A(0:2,0:2) consists of
conjugate-transpose of the last three columns of AP lower.
To denote conjugate we place -- above the element. This covers the case
N even and TRANSR = 'N'.
RFP A RFP A
-- -- --
03 04 05 33 43 53
-- --
13 14 15 00 44 54
--
23 24 25 10 11 55
33 34 35 20 21 22
--
00 44 45 30 31 32
-- --
01 11 55 40 41 42
-- -- --
02 12 22 50 51 52
Now let TRANSR = 'C'. RFP A in both UPLO cases is just the conjugate-
transpose of RFP A above. One therefore gets:
RFP A RFP A
-- -- -- -- -- -- -- -- -- --
03 13 23 33 00 01 02 33 00 10 20 30 40 50
-- -- -- -- -- -- -- -- -- --
04 14 24 34 44 11 12 43 44 11 21 31 41 51
-- -- -- -- -- -- -- -- -- --
05 15 25 35 45 55 22 53 54 55 22 32 42 52
We next consider Standard Packed Format when N is odd.
We give an example where N = 5.
AP is Upper AP is Lower
00 01 02 03 04 00
11 12 13 14 10 11
22 23 24 20 21 22
33 34 30 31 32 33
44 40 41 42 43 44
Let TRANSR = 'N'. RFP holds AP as follows:
For UPLO = 'U' the upper trapezoid A(0:4,0:2) consists of the last
three columns of AP upper. The lower triangle A(3:4,0:1) consists of
conjugate-transpose of the first two columns of AP upper.
For UPLO = 'L' the lower trapezoid A(0:4,0:2) consists of the first
three columns of AP lower. The upper triangle A(0:1,1:2) consists of
conjugate-transpose of the last two columns of AP lower.
To denote conjugate we place -- above the element. This covers the case
N odd and TRANSR = 'N'.
RFP A RFP A
-- --
02 03 04 00 33 43
--
12 13 14 10 11 44
22 23 24 20 21 22
--
00 33 34 30 31 32
-- --
01 11 44 40 41 42
Now let TRANSR = 'C'. RFP A in both UPLO cases is just the conjugate-
transpose of RFP A above. One therefore gets:
RFP A RFP A
-- -- -- -- -- -- -- -- --
02 12 22 00 01 00 10 20 30 40 50
-- -- -- -- -- -- -- -- --
03 13 23 33 11 33 11 21 31 41 51
-- -- -- -- -- -- -- -- --
04 14 24 34 44 43 44 22 32 42 52
7 Nov 2015 ztftri(3P)