stbsv - solve one of the systems of equations A*x = b, or A'*x = b
SUBROUTINE STBSV( UPLO, TRANSA, DIAG, N, NDIAG, A, LDA, Y, INCY) CHARACTER * 1 UPLO, TRANSA, DIAG INTEGER N, NDIAG, LDA, INCY REAL A(LDA,*), Y(*)
SUBROUTINE STBSV_64( UPLO, TRANSA, DIAG, N, NDIAG, A, LDA, Y, INCY) CHARACTER * 1 UPLO, TRANSA, DIAG INTEGER*8 N, NDIAG, LDA, INCY REAL A(LDA,*), Y(*)
SUBROUTINE TBSV( UPLO, [TRANSA], DIAG, [N], NDIAG, A, [LDA], Y, * [INCY]) CHARACTER(LEN=1) :: UPLO, TRANSA, DIAG INTEGER :: N, NDIAG, LDA, INCY REAL, DIMENSION(:) :: Y REAL, DIMENSION(:,:) :: A
SUBROUTINE TBSV_64( UPLO, [TRANSA], DIAG, [N], NDIAG, A, [LDA], Y, * [INCY]) CHARACTER(LEN=1) :: UPLO, TRANSA, DIAG INTEGER(8) :: N, NDIAG, LDA, INCY REAL, DIMENSION(:) :: Y REAL, DIMENSION(:,:) :: A
#include <sunperf.h>
void stbsv(char uplo, char transa, char diag, int n, int ndiag, float *a, int lda, float *y, int incy);
void stbsv_64(char uplo, char transa, char diag, long n, long ndiag, float *a, long lda, float *y, long incy);
stbsv solves one of the systems of equations A*x = b, or A'*x = b, where b and x are n element vectors and A is an n by n unit, or non-unit, upper or lower triangular band matrix, with ( ndiag + 1 ) diagonals.
No test for singularity or near-singularity is included in this routine. Such tests must be performed before calling this routine.
UPLO = 'U' or 'u' A is an upper triangular matrix.
UPLO = 'L' or 'l' A is a lower triangular matrix.
Unchanged on exit.
TRANSA = 'N' or 'n' A*x = b.
TRANSA = 'T' or 't' A'*x = b.
TRANSA = 'C' or 'c' A'*x = b.
Unchanged on exit.
DIAG = 'U' or 'u' A is assumed to be unit triangular.
DIAG = 'N' or 'n' A is not assumed to be unit triangular.
Unchanged on exit.
DO 20, J = 1, N M = NDIAG + 1 - J DO 10, I = MAX( 1, J - NDIAG ), J A( M + I, J ) = matrix( I, J ) 10 CONTINUE 20 CONTINUE
Before entry with UPLO = 'L' or 'l', the leading ( ndiag + 1 ) by n part of the array A must contain the lower triangular band part of the matrix of coefficients, supplied column by column, with the leading diagonal of the matrix in row 1 of the array, the first sub-diagonal starting at position 1 in row 2, and so on. The bottom right ndiag by ndiag triangle of the array A is not referenced. The following program segment will transfer a lower triangular band matrix from conventional full matrix storage to band storage:
DO 20, J = 1, N M = 1 - J DO 10, I = J, MIN( N, J + NDIAG ) A( M + I, J ) = matrix( I, J ) 10 CONTINUE 20 CONTINUE
Note that when DIAG = 'U' or 'u' the elements of the array A corresponding to the diagonal elements of the matrix are not referenced, but are assumed to be unity. Unchanged on exit.