dtbtrs

NAME

dtbtrs - solve a triangular system of the form A * X = B or A**T * X = B,

SYNOPSIS

  SUBROUTINE DTBTRS( UPLO, TRANSA, DIAG, N, NDIAG, NRHS, A, LDA, B, 
 *      LDB, INFO)
  CHARACTER * 1 UPLO, TRANSA, DIAG
  INTEGER N, NDIAG, NRHS, LDA, LDB, INFO
  DOUBLE PRECISION A(LDA,*), B(LDB,*)
 
  SUBROUTINE DTBTRS_64( UPLO, TRANSA, DIAG, N, NDIAG, NRHS, A, LDA, B, 
 *      LDB, INFO)
  CHARACTER * 1 UPLO, TRANSA, DIAG
  INTEGER*8 N, NDIAG, NRHS, LDA, LDB, INFO
  DOUBLE PRECISION A(LDA,*), B(LDB,*)

F95 INTERFACE

  SUBROUTINE TBTRS( UPLO, TRANSA, DIAG, N, NDIAG, NRHS, A, [LDA], B, 
 *       [LDB], [INFO])
  CHARACTER(LEN=1) :: UPLO, TRANSA, DIAG
  INTEGER :: N, NDIAG, NRHS, LDA, LDB, INFO
  REAL(8), DIMENSION(:,:) :: A, B
 
  SUBROUTINE TBTRS_64( UPLO, TRANSA, DIAG, N, NDIAG, NRHS, A, [LDA], 
 *       B, [LDB], [INFO])
  CHARACTER(LEN=1) :: UPLO, TRANSA, DIAG
  INTEGER(8) :: N, NDIAG, 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 ndiag, int nrhs, double *a, int lda, double *b, int ldb, int *info);

void dtbtrs_64(char uplo, char transa, char diag, long n, long ndiag, long nrhs, double *a, long lda, double *b, long ldb, long *info);

PURPOSE

dtbtrs solves a triangular system of the form

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)
* TRANSA (input): Specifies the form the system of equations:
* DIAG (input)
* N (input): The order of the matrix A. N >= 0.
* NDIAG (input): The number of superdiagonals or subdiagonals of the triangular band matrix A. NDIAG >= 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 >= NDIAG+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)