Seriously, no "PMT" in c# is listed? Am I missing something or do you guys need to calculate mortgage payments so often that it needs to be a built in function

Seriously, no "PMT" in c# is listed? Am I missing something or do you guys need to calculate mortgage payments so often that it needs to be a built in function of a language? There are a couple of valid points in this article, the rest is hogwash.