Finding the intersection of curves

[nsmoker]

For a graph of a function, use a binary search like algorithm splitting on the minimum as found using optimise.

When all we have are points, first split each line when a single x coord maps to two y coords, then interpolate, then use algorithm above.

[sfogarty]

To deal with curves that backtrack on the x-plane, split both curves into segments, and then check all segments pairwise.