dgbmv(3P) Sun Performance Library dgbmv(3P)NAMEdgbmv - perform one of the matrix-vector operations y := alpha*A*x +
beta*y or y := alpha*A'*x + beta*y
SYNOPSIS
SUBROUTINE DGBMV(TRANSA, M, N, KL, KU, ALPHA, A, LDA, X, INCX,
BETA, Y, INCY)
CHARACTER * 1 TRANSA
INTEGER M, N, KL, KU, LDA, INCX, INCY
DOUBLE PRECISION ALPHA, BETA
DOUBLE PRECISION A(LDA,*), X(*), Y(*)
SUBROUTINE DGBMV_64(TRANSA, M, N, KL, KU, ALPHA, A, LDA, X,
INCX, BETA, Y, INCY)
CHARACTER * 1 TRANSA
INTEGER*8 M, N, KL, KU, LDA, INCX, INCY
DOUBLE PRECISION ALPHA, BETA
DOUBLE PRECISION A(LDA,*), X(*), Y(*)
F95 INTERFACE
SUBROUTINE GBMV([TRANSA], [M], [N], KL, KU, ALPHA, A, [LDA], X,
[INCX], BETA, Y, [INCY])
CHARACTER(LEN=1) :: TRANSA
INTEGER :: M, N, KL, KU, LDA, INCX, INCY
REAL(8) :: ALPHA, BETA
REAL(8), DIMENSION(:) :: X, Y
REAL(8), DIMENSION(:,:) :: A
SUBROUTINE GBMV_64([TRANSA], [M], [N], KL, KU, ALPHA, A, [LDA],
X, [INCX], BETA, Y, [INCY])
CHARACTER(LEN=1) :: TRANSA
INTEGER(8) :: M, N, KL, KU, LDA, INCX, INCY
REAL(8) :: ALPHA, BETA
REAL(8), DIMENSION(:) :: X, Y
REAL(8), DIMENSION(:,:) :: A
C INTERFACE
#include <sunperf.h>
void dgbmv(char transa, int m, int n, int kl, int ku, 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 kl, long ku, double
alpha, double *a, long lda, double *x, long incx, double
beta, double *y, long incy);
PURPOSEdgbmv 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 kl sub-diagonals
and ku super-diagonals.
ARGUMENTS
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.
TRANSA is defaulted to 'N' for F95 INTERFACE.
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.
KL (input)
On entry, KL specifies the number of sub-diagonals of the
matrix A. KL >= 0. Unchanged on exit.
KU (input)
On entry, KU specifies the number of super-diagonals of the
matrix A. KU >= 0. Unchanged on exit.
ALPHA (input)
On entry, ALPHA specifies the scalar alpha. Unchanged on
exit.
A (input)
Before entry, the leading ( kl + ku + 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 ( ku + 1 ) of the array, the first super-diagonal start‐
ing at position 2 in row ku, the first sub-diagonal starting
at position 1 in row ( ku + 2 ), and so on. Elements in the
array A that do not correspond to elements in the band matrix
(such as the top left ku by ku 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 = KU + 1 - J
DO 10, I = MAX( 1, J - KU ), MIN( M, J + KL )
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 >= ( kl + ku + 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 sup‐
plied 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.
6 Mar 2009 dgbmv(3P)
