dtptrs(3P) Sun Performance Library dtptrs(3P)NAMEdtptrs - solve a triangular system of the form A * X = B or A**T * X
= B,
SYNOPSIS
SUBROUTINE DTPTRS(UPLO, TRANSA, DIAG, N, NRHS, A, B, LDB, INFO)
CHARACTER * 1 UPLO, TRANSA, DIAG
INTEGER N, NRHS, LDB, INFO
DOUBLE PRECISION A(*), B(LDB,*)
SUBROUTINE DTPTRS_64(UPLO, TRANSA, DIAG, N, NRHS, A, B, LDB, INFO)
CHARACTER * 1 UPLO, TRANSA, DIAG
INTEGER*8 N, NRHS, LDB, INFO
DOUBLE PRECISION A(*), B(LDB,*)
F95 INTERFACE
SUBROUTINE TPTRS(UPLO, [TRANSA], DIAG, [N], [NRHS], A, B, [LDB], [INFO])
CHARACTER(LEN=1) :: UPLO, TRANSA, DIAG
INTEGER :: N, NRHS, LDB, INFO
REAL(8), DIMENSION(:) :: A
REAL(8), DIMENSION(:,:) :: B
SUBROUTINE TPTRS_64(UPLO, [TRANSA], DIAG, [N], [NRHS], A, B, [LDB], [INFO])
CHARACTER(LEN=1) :: UPLO, TRANSA, DIAG
INTEGER(8) :: N, NRHS, LDB, INFO
REAL(8), DIMENSION(:) :: A
REAL(8), DIMENSION(:,:) :: B
C INTERFACE
#include <sunperf.h>
void dtptrs(char uplo, char transa, char diag, int n, int nrhs, double
*a, double *b, int ldb, int *info);
void dtptrs_64(char uplo, char transa, char diag, long n, long nrhs,
double *a, double *b, long ldb, long *info);
PURPOSEdtptrs solves a triangular system of the form
A * X = B or A**T * X = B
where A is a triangular matrix of order N stored in packed format, and
B is an N-by-NRHS matrix. A check is made to verify that A is nonsin‐
gular.
ARGUMENTS
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 = Transpose)
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) DOUBLE PRECISION array, dimension (N*(N+1)/2)
The upper or lower triangular matrix A, packed columnwise in
a linear array. The j-th column of A is stored in the array
A as follows: if UPLO = 'U', A(i + (j-1)*j/2) = A(i,j) for
1<=i<=j; if UPLO = 'L', A(i + (j-1)*(2*n-j)/2) = A(i,j) for
j<=i<=n.
B (input/output) DOUBLE PRECISION array, dimension (LDB,NRHS)
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 illegal 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.
6 Mar 2009 dtptrs(3P)
