That may be because there isn't one.
This is not true there is like 7 or 8 equations that all do the same thing for the most part. 1 or 2 of them being the most popular. But again pointing to tool to do the work for me is not what I am looking for. I want to talk to someone that knows, uses and understands the equations.
Also I am not a C programmer, I might be able to get what I need from it with much effort. Dont get me wrong I am a tech and can ussually read and alter code as needed, but C & C++ is a little over my head. But just pointing to calculaters is ug for me.