Background: I use code from [An Efficient Test For A Point To Be In A Convex Polygon](http://demonstrations.wolfram.com/AnEfficientTestForAPointToBeInAConvexPolygon/) Wolfram Demonstration to check if a point ( mouse pointer ) is in a ( convex ) polygon. Clearly this code fails for non-convex polygons.

**Question: I am looking for an efficient routine to check if a 2D-point is in a polygon.**