Daily Equation #12 - Ellipse x^2/a + y^2/b = 1

This is Day 12 of my collection of printable equations. To see the whole collection, go to: http://www.thingiverse.com/thing:227210

Things are a little hectic this week, so I decided to go with something simple, an ellipse (http://en.wikipedia.org/wiki/Ellipse). The equation is a variant of the circle (Day 8, x^2 + y^2 = a http://www.thingiverse.com/thing:233659), but with different divisors for x and y. So, x^2/a + y^2/b = 1. A and b control the maximum/minimum in the x and y direction, resp