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

Chapter 2 Basic Vector Operations 69
Sparse elementary vector operation SAXPYI/DAXPYI/CAXPYI/ZAXPYI
INTEGER*8 m, indx(m)
COMPLEX*8 a, x(m), y(n)
CALL CAXPYI(m, a, x, indx, y)
INTEGER*8 m, indx(m)
COMPLEX*16 a, x(m), y(n)
CALL ZAXPYI(m, a, x, indx, y)
Input m Number of interesting elements of x, m ≤ n, where n is
the length of y. If m ≤ 0, the subprograms do not
reference x, indx, or y.
a The scalar a.
x Array of length m containing the interesting elements
of x. x(j)=x
i
if indx(j)=i.