# Forward differencing (and back)

I read that "forward differencing" is a method for "evaluating polynomials at uniformly spaced intervals". That is, if I have parabola like $y = x^2$ and increase $x$ by 1, I can use it.

My question is, does it also work "backwards"? If I want uniformly spaced $y$ values (say by 1 as well), is it somehow possible to use it? How do I choose the "differences" so that the output is regularly spaced?

• Hint: use $ to start a math formula and close it with other $, instead of `. – Sigur Jan 26 '13 at 23:37