numerical
Suppose that Ï•(h) is an approximation to some quantity M for every h > 0
and that
M = Ï•(h) + a2h^2 + a4h^4+ a6h^6 + . . .
for some constants a2, a4, a6, . . . Use the values Ï•(h), Ï•(h/
3 ) and Ï•(h/
9 ) to produce an O(h^6)
approximation to M.