ssbmv(3P) Sun Performance Library ssbmv(3P)NAMEssbmv - perform the matrix-vector operation y := alpha*A*x + beta*y
SYNOPSIS
SUBROUTINE SSBMV(UPLO, N, K, ALPHA, A, LDA, X, INCX, BETA, Y,
INCY)
CHARACTER * 1 UPLO
INTEGER N, K, LDA, INCX, INCY
REAL ALPHA, BETA
REAL A(LDA,*), X(*), Y(*)
SUBROUTINE SSBMV_64(UPLO, N, K, ALPHA, A, LDA, X, INCX, BETA, Y,
INCY)
CHARACTER * 1 UPLO
INTEGER*8 N, K, LDA, INCX, INCY
REAL ALPHA, BETA
REAL A(LDA,*), X(*), Y(*)
F95 INTERFACE
SUBROUTINE SBMV(UPLO, [N], K, ALPHA, A, [LDA], X, [INCX], BETA,
Y, [INCY])
CHARACTER(LEN=1) :: UPLO
INTEGER :: N, K, LDA, INCX, INCY
REAL :: ALPHA, BETA
REAL, DIMENSION(:) :: X, Y
REAL, DIMENSION(:,:) :: A
SUBROUTINE SBMV_64(UPLO, [N], K, ALPHA, A, [LDA], X, [INCX],
BETA, Y, [INCY])
CHARACTER(LEN=1) :: UPLO
INTEGER(8) :: N, K, LDA, INCX, INCY
REAL :: ALPHA, BETA
REAL, DIMENSION(:) :: X, Y
REAL, DIMENSION(:,:) :: A
C INTERFACE
#include <sunperf.h>
void ssbmv(char uplo, int n, int k, float alpha, float *a, int lda,
float *x, int incx, float beta, float *y, int incy);
void ssbmv_64(char uplo, long n, long k, float alpha, float *a, long
lda, float *x, long incx, float beta, float *y, long incy);
PURPOSEssbmv performs the matrix-vector operation y := alpha*A*x + beta*y,
where alpha and beta are scalars, x and y are n element vectors and A
is an n by n symmetric band matrix, with k super-diagonals.
ARGUMENTS
UPLO (input)
On entry, UPLO specifies whether the upper or lower triangu‐
lar part of the band matrix A is being supplied as follows:
UPLO = 'U' or 'u' The upper triangular part of A is being
supplied.
UPLO = 'L' or 'l' The lower triangular part of A is being
supplied.
Unchanged on exit.
N (input)
On entry, N specifies the order of the matrix A. N >= 0.
Unchanged on exit.
K (input)
On entry, K specifies the number of super-diagonals of the
matrix A. K >= 0. Unchanged on exit.
ALPHA (input)
On entry, ALPHA specifies the scalar alpha. Unchanged on
exit.
A (input)
Before entry with UPLO = 'U' or 'u', the leading ( k + 1 ) by
n part of the array A must contain the upper triangular band
part of the symmetric matrix, supplied column by column, with
the leading diagonal of the matrix in row ( k + 1 ) of the
array, the first super-diagonal starting at position 2 in row
k, and so on. The top left k by k triangle of the array A is
not referenced. The following program segment will transfer
the upper triangular part of a symmetric band matrix from
conventional full matrix storage to band storage:
DO 20, J = 1, N
M = K + 1 - J
DO 10, I = MAX( 1, J - K ), J
A( M + I, J ) = matrix( I, J )
10 CONTINUE
20 CONTINUE
Before entry with UPLO = 'L' or 'l', the leading ( k + 1 ) by
n part of the array A must contain the lower triangular band
part of the symmetric matrix, 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 k by k triangle of the array A is not
referenced. The following program segment will transfer the
lower triangular part of a symmetric band matrix from conven‐
tional full matrix storage to band storage:
DO 20, J = 1, N
M = 1 - J
DO 10, I = J, MIN( N, J + K )
A( M + 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 >= ( k + 1 ). Unchanged on
exit.
X (input)
( 1 + ( n - 1 )*abs( INCX ) ). 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. Unchanged on exit.
Y (input/output)
( 1 + ( n - 1 )*abs( INCY ) ). 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 ssbmv(3P)
