axpy

import mir.series;
auto x = series([0, 3, 5, 9, 10], [1.0, 3, 4, 9, 13]);
auto y = [0.0, 1.0, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12];
axpy(2.0, x, y);
assert(y == [2.0, 1.0, 2, 9, 4, 13, 6, 7, 8, 27, 36, 11, 12]);