dgbmv - perform one of the matrix-vector operations y := alpha*A*x + beta*y or y := alpha*A'*x + beta*y
SUBROUTINE DGBMV( TRANSA, M, N, NSUB, NSUPER, ALPHA, A, LDA, X,
* INCX, BETA, Y, INCY)
CHARACTER * 1 TRANSA
INTEGER M, N, NSUB, NSUPER, LDA, INCX, INCY
DOUBLE PRECISION ALPHA, BETA
DOUBLE PRECISION A(LDA,*), X(*), Y(*)
SUBROUTINE DGBMV_64( TRANSA, M, N, NSUB, NSUPER, ALPHA, A, LDA, X,
* INCX, BETA, Y, INCY)
CHARACTER * 1 TRANSA
INTEGER*8 M, N, NSUB, NSUPER, LDA, INCX, INCY
DOUBLE PRECISION ALPHA, BETA
DOUBLE PRECISION A(LDA,*), X(*), Y(*)
SUBROUTINE GBMV( [TRANSA], [M], [N], NSUB, NSUPER, ALPHA, A, [LDA],
* X, [INCX], BETA, Y, [INCY])
CHARACTER(LEN=1) :: TRANSA
INTEGER :: M, N, NSUB, NSUPER, LDA, INCX, INCY
REAL(8) :: ALPHA, BETA
REAL(8), DIMENSION(:) :: X, Y
REAL(8), DIMENSION(:,:) :: A
SUBROUTINE GBMV_64( [TRANSA], [M], [N], NSUB, NSUPER, ALPHA, A, [LDA],
* X, [INCX], BETA, Y, [INCY])
CHARACTER(LEN=1) :: TRANSA
INTEGER(8) :: M, N, NSUB, NSUPER, LDA, INCX, INCY
REAL(8) :: ALPHA, BETA
REAL(8), DIMENSION(:) :: X, Y
REAL(8), DIMENSION(:,:) :: A
#include <sunperf.h>
void dgbmv(char transa, int m, int n, int nsub, int nsuper, double alpha, double *a, int lda, double *x, int incx, double beta, double *y, int incy);
void dgbmv_64(char transa, long m, long n, long nsub, long nsuper, double alpha, double *a, long lda, double *x, long incx, double beta, double *y, long incy);
dgbmv performs one of the matrix-vector operations
y := alpha*A*x + beta*y or y := alpha*A'*x + beta*y,
where alpha and beta are scalars, x and y are vectors and A is an
m by n band matrix, with nsub sub-diagonals and nsuper super-diagonals.
- TRANSA (input)
On entry, TRANSA specifies the operation to be performed as
follows:
TRANSA = 'N' or 'n' y : = alpha*A*x + beta*y.
TRANSA = 'T' or 't' y : = alpha*A'*x + beta*y.
TRANSA = 'C' or 'c' y : = alpha*A'*x + beta*y.
Unchanged on exit.
- M (input)
On entry, M specifies the number of rows of the matrix A.
M > = 0.
Unchanged on exit.
- N (input)
On entry, N specifies the number of columns of the matrix A.
N > = 0.
Unchanged on exit.
- NSUB (input)
On entry, NSUB specifies the number of sub-diagonals of the
matrix A. NSUB > = 0.
Unchanged on exit.
- NSUPER (input)
On entry, NSUPER specifies the number of super-diagonals of the
matrix A. NSUPER > = 0.
Unchanged on exit.
- ALPHA (input)
On entry, ALPHA specifies the scalar alpha.
Unchanged on exit.
- A (input)
Before entry, the leading ( nsub + nsuper + 1 ) by n part of the
array A must contain the matrix of coefficients, supplied
column by column, with the leading diagonal of the matrix in
row ( nsuper + 1 ) of the array, the first super-diagonal
starting at position 2 in row nsuper, the first sub-diagonal
starting at position 1 in row ( nsuper + 2 ), and so on.
Elements in the array A that do not correspond to elements
in the band matrix (such as the top left nsuper by nsuper triangle)
are not referenced.
The following program segment will transfer a band matrix
from conventional full matrix storage to band storage:
DO 20, J = 1, N
K = NSUPER + 1 - J
DO 10, I = MAX( 1, J - NSUPER ), MIN( M, J + NSUB )
A( K + I, J ) = matrix( I, J )
10 CONTINUE
20 CONTINUE
Unchanged on exit.
- LDA (input)
On entry, LDA specifies the first dimension of A as declared
in the calling (sub) program. LDA > = ( nsub + nsuper + 1 ).
Unchanged on exit.
- X (input)
( 1 + ( n - 1 )*abs( INCX ) ) when TRANSA = 'N' or 'n'
and at least
( 1 + ( m - 1 )*abs( INCX ) ) otherwise.
Before entry, the incremented array X must contain the
vector x.
Unchanged on exit.
- INCX (input)
On entry, INCX specifies the increment for the elements of
X. INCX < > 0.
Unchanged on exit.
- BETA (input)
On entry, BETA specifies the scalar beta. When BETA is
supplied as zero then Y need not be set on input.
Unchanged on exit.
- Y (input/output)
( 1 + ( m - 1 )*abs( INCY ) ) when TRANSA = 'N' or 'n'
and at least
( 1 + ( n - 1 )*abs( INCY ) ) otherwise.
Before entry, the incremented array Y must contain the
vector y. On exit, Y is overwritten by the updated vector y.
- INCY (input)
On entry, INCY specifies the increment for the elements of
Y. INCY < > 0.
Unchanged on exit.