用于查找点是否在2D多边形内作为标准测试的替代测试失败

I wrote the following code to find whether a point is inside a polygon or not -- the algorithm using crossing number and winding number tests. However, I find that these tests fail when my polygon is: (10,10),(10,20),(20,20) and (20,10) and the point which I want to find whether it is in the polygon is: (20,15). My points here represent the (latitude, longitude) of locations.I wrote the following code to find whether a po