Contents
ztrtrs - solve a triangular system of the form A * X = B,
A**T * X = B, or A**H * X = B,
SUBROUTINE ZTRTRS(UPLO, TRANSA, DIAG, N, NRHS, A, LDA, B, LDB, INFO)
CHARACTER * 1 UPLO, TRANSA, DIAG
DOUBLE COMPLEX A(LDA,*), B(LDB,*)
INTEGER N, NRHS, LDA, LDB, INFO
SUBROUTINE ZTRTRS_64(UPLO, TRANSA, DIAG, N, NRHS, A, LDA, B, LDB,
INFO)
CHARACTER * 1 UPLO, TRANSA, DIAG
DOUBLE COMPLEX A(LDA,*), B(LDB,*)
INTEGER*8 N, NRHS, LDA, LDB, INFO
F95 INTERFACE
SUBROUTINE TRTRS(UPLO, [TRANSA], DIAG, [N], [NRHS], A, [LDA], B, [LDB],
[INFO])
CHARACTER(LEN=1) :: UPLO, TRANSA, DIAG
COMPLEX(8), DIMENSION(:,:) :: A, B
INTEGER :: N, NRHS, LDA, LDB, INFO
SUBROUTINE TRTRS_64(UPLO, [TRANSA], DIAG, [N], [NRHS], A, [LDA], B, [LDB],
[INFO])
CHARACTER(LEN=1) :: UPLO, TRANSA, DIAG
COMPLEX(8), DIMENSION(:,:) :: A, B
INTEGER(8) :: N, NRHS, LDA, LDB, INFO
C INTERFACE
#include <sunperf.h>
void ztrtrs(char uplo, char transa, char diag, int n, int
nrhs, doublecomplex *a, int lda, doublecomplex *b,
int ldb, int *info);
void ztrtrs_64(char uplo, char transa, char diag, long n,
long nrhs, doublecomplex *a, long lda, doublecom-
plex *b, long ldb, long *info);
ztrtrs solves a triangular system of the form
A * X = B, A**T * X = B, or A**H * X = B
where A is a triangular matrix of order N, and B is an N-
by-NRHS matrix. A check is made to verify that A is non-
singular.
UPLO (input)
= 'U': A is upper triangular;
= 'L': A is lower triangular.
TRANSA (input)
Specifies the form of the system of equations:
= 'N': A * X = B (No transpose)
= 'T': A**T * X = B (Transpose)
= 'C': A**H * X = B (Conjugate transpose)
TRANSA is defaulted to 'N' for F95 INTERFACE.
DIAG (input)
= 'N': A is non-unit triangular;
= 'U': A is unit triangular.
N (input) The order of the matrix A. N >= 0.
NRHS (input)
The number of right hand sides, i.e., the number
of columns of the matrix B. NRHS >= 0.
A (input) The triangular matrix A. If UPLO = 'U', the lead-
ing N-by-N upper triangular part of the array A
contains the upper triangular matrix, and the
strictly lower triangular part of A is not refer-
enced. If UPLO = 'L', the leading N-by-N lower
triangular part of the array A contains the lower
triangular matrix, and the strictly upper triangu-
lar part of A is not referenced. If DIAG = 'U',
the diagonal elements of A are also not referenced
and are assumed to be 1.
LDA (input)
The leading dimension of the array A. LDA >=
max(1,N).
B (input/output)
On entry, the right hand side matrix B. On exit,
if INFO = 0, the solution matrix X.
LDB (input)
The leading dimension of the array B. LDB >=
max(1,N).
INFO (output)
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an ille-
gal value
> 0: if INFO = i, the i-th diagonal element of A
is zero, indicating that the matrix is singular
and the solutions X have not been computed.