I’ve added an quadratic interpolator to my website similar to the linear interpolator I wrote earlier. I find this useful when I’m doing a brute force search for some parameter and I’m unwilling or unable to do anything fancier.
CodeProject just posted my article Filling in the gaps: simple interpolation.
I added a form to my website yesterday that does linear interpolation. If you enter (x1, y1) and (x2, y2), it will predict x3 given y3or vice versa by fitting a straight line to the first two points. It’s a simple calculation, but it comes up just often enough that it would be handy to have a page to do it.