This may seem crazy but if you are not after a graph tha tis going to be joining lines after plotting points then you could create your own library in not too much time i imagine. Thus it would be completely customised to you and will require little maths to work out. However, if you require it to plot join points with curves etc then the mathsbehind it will be a bit more complex, but I'm sure there are adequate exaples out there on the internet. It would just be a case of finding out where it is located
Regards.
Chris