HP MLIB User's Guide Vol. 1 7th Ed.

Chapter 3 Basic Matrix Operations 271
Matrix-vector multiply SSYMV/DSYMV/CHEMV/ZHEMV
CHARACTER*1 uplo
INTEGER*4 n, lda, incx, incy
COMPLEX*16 alpha, beta, a(lda, n), x(lenx), y(leny)
CALL ZHEMV(uplo, n, alpha, a, lda, x, incx, beta, y, incy)
VECLIB8:
CHARACTER*1 uplo
INTEGER*8 n, lda, incx, incy
REAL*4 alpha, beta, a(lda, n), x(lenx), y(leny)
CALL SSYMV(uplo, n, alpha, a, lda, x, incx, beta, y, incy)
CHARACTER*1 uplo
INTEGER*8 n, lda, incx, incy
REAL*8 alpha, beta, a(lda, n), x(lenx), y(leny)
CALL DSYMV(uplo, n, alpha, a, lda, x, incx, beta, y, incy)
CHARACTER*1 uplo
INTEGER*8 n, lda, incx, incy
COMPLEX*8 alpha, beta, a(lda, n), x(lenx), y(leny)
CALL CHEMV(uplo, n, alpha, a, lda, x, incx, beta, y, incy)
CHARACTER*1 uplo
INTEGER*8 n, lda, incx, incy
COMPLEX*16 alpha, beta, a(lda, n), x(lenx), y(leny)
CALL ZHEMV(uplo, n, alpha, a, lda, x, incx, beta, y, incy)
Input uplo Upper/lower triangular option for A:
’L’ or ’l’ Reference only the lower triangle of A.
’U’ or ’u’ Reference only the upper triangle
of A.
n Number of rows and columns in matrix A, n ≥ 0. If
n = 0, the subprograms do not reference a, x, or y.
alpha The scalar α. If alpha = 0, the subprograms compute
y ←βy without referencing a or x.
a Array whose upper or lower triangle, as specified by
uplo, contains the upper or lower triangle of an n-by-n
real symmetric or complex Hermitian matrix A. The
other triangle of a is not referenced.
lda The leading dimension of array a as declared in the
calling program unit, with lda ≥ max(n,1).
x Array of length lenx = (n−1)×|incx|+1 containing the
n-vector x.