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

252 HP MLIB User’s Guide
SSPMV/DSPMV/CHPMV/ZHPMV Matrix-vector multiply
Input uplo Upper/lower triangular option for A:
’L’ or ’l’ The lower triangle of A is stored in the
packed array.
’U’ or ’u’ The upper triangle of A is stored in
the packed array.
n Number of rows and columns in matrix A, n ≥ 0. If
n = 0, the subprograms do not reference ap, x, or y.
alpha The scalar α. If alpha = 0, the subprograms compute
y ←βy without referencing ap or x.
ap Array of length lenap = n×(n+1)/2 containing the upper
or lower triangle, as specified by uplo, of an n-by-n real
symmetric or complex Hermitian matrix A, stored by
columns in the packed form described above.
x Array of length lenx = (n−1)×|incx|+1 containing the
n-vector x.
incx Increment for the array x, incx ≠ 0:
incx > 0 x is stored forward in array x; that is,
x
i
is stored in x((i−1)×incx+1).
incx < 0 x is stored backward in array x; that
is, x
i
is stored in x((i−n)×incx+1).
Use incx = 1 if the vector x is stored contiguously in
array x, that is, if x
i
is stored in x(i). Refer to “BLAS
Indexing Conventions” in the introduction to
Chapter 2.
beta The scalar β.
y Array of length leny = (n−1)×|incy|+1 containing the
n-vector y. Not used as input if beta = 0.
incy Increment for the array y, incy ≠ 0:
incy > 0 y is stored forward in array y; that is,
y
i
is stored in y((i−1)×incy+1).
incy < 0 y is stored backward in array y; that
is, y
i
is stored in y((i−n)×incy+1).
Use incy = 1 if the vector y is stored contiguously in
array y, that is, if y
i
is stored in y(i). Refer to “BLAS
Indexing Conventions” in the introduction to
Chapter 2.