dtbtrs(3P) Sun Performance Library dtbtrs(3P)NAMEdtbtrs - solve a triangular system of the form A * X = B or A**T * X
= B,
SYNOPSIS
SUBROUTINE DTBTRS(UPLO, TRANSA, DIAG, N, KD, NRHS, A, LDA, B, LDB,
INFO)
CHARACTER * 1 UPLO, TRANSA, DIAG
INTEGER N, KD, NRHS, LDA, LDB, INFO
DOUBLE PRECISION A(LDA,*), B(LDB,*)
SUBROUTINE DTBTRS_64(UPLO, TRANSA, DIAG, N, KD, NRHS, A, LDA, B,
LDB, INFO)
CHARACTER * 1 UPLO, TRANSA, DIAG
INTEGER*8 N, KD, NRHS, LDA, LDB, INFO
DOUBLE PRECISION A(LDA,*), B(LDB,*)
F95 INTERFACE
SUBROUTINE TBTRS(UPLO, [TRANSA], DIAG, [N], KD, [NRHS], A, [LDA], B,
[LDB], [INFO])
CHARACTER(LEN=1) :: UPLO, TRANSA, DIAG
INTEGER :: N, KD, NRHS, LDA, LDB, INFO
REAL(8), DIMENSION(:,:) :: A, B
SUBROUTINE TBTRS_64(UPLO, [TRANSA], DIAG, [N], KD, [NRHS], A, [LDA], B,
[LDB], [INFO])
CHARACTER(LEN=1) :: UPLO, TRANSA, DIAG
INTEGER(8) :: N, KD, NRHS, LDA, LDB, INFO
REAL(8), DIMENSION(:,:) :: A, B
C INTERFACE
#include <sunperf.h>
void dtbtrs(char uplo, char transa, char diag, int n, int kd, int nrhs,
double *a, int lda, double *b, int ldb, int *info);
void dtbtrs_64(char uplo, char transa, char diag, long n, long kd, long
nrhs, double *a, long lda, double *b, long ldb, long *info);
PURPOSEdtbtrs solves a triangular system of the form
A * X = B or A**T * X = B
where A is a triangular band matrix of order N, and B is an N-by NRHS
matrix. A check is made to verify that A is nonsingular.
ARGUMENTS
UPLO (input)
= 'U': A is upper triangular;
= 'L': A is lower triangular.
TRANSA (input)
Specifies the form 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.
KD (input)
The number of superdiagonals or subdiagonals of the triangu‐
lar band matrix A. KD >= 0.
NRHS (input)
The number of right hand sides, i.e., the number of columns
of the matrix B. NRHS >= 0.
A (input) The upper or lower triangular band matrix A, stored in the
first kd+1 rows of A. The j-th column of A is stored in the
j-th column of the array A as follows: if UPLO = 'U',
A(kd+1+i-j,j) = A(i,j) for max(1,j-kd)<=i<=j; if UPLO = 'L',
A(1+i-j,j) = A(i,j) for j<=i<=min(n,j+kd). If DIAG = 'U',
the diagonal elements of A are not referenced and are assumed
to be 1.
LDA (input)
The leading dimension of the array A. LDA >= KD+1.
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 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 dtbtrs(3P)
