Contents
ssbmv - perform the matrix-vector operation y := alpha*A*x
+ beta*y
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);
ssbmv performs the matrix-vector operation y := alpha*A*x +
beta*y, where alpha and beta are scalars, x and y are n ele-
ment vectors and A is an n by n symmetric band matrix, with
k super-diagonals.
UPLO (input)
On entry, UPLO specifies whether the upper or
lower triangular 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 lead-
ing diagonal of the matrix in row ( k + 1 ) of the
array, the first super-diagonal starting at posi-
tion 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 lead-
ing 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 conventional
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.