Open source loan amortization schedule

I suppose this is a follow-up to this previous SO post, but I have been searching for an open-source library that is usable with Objective-C that will take loan parameters and gen开发者_StackOverflowerate an amortization schedule. I know there are tons of iPhone apps out there that generate amortization schedules, but what libraries do they use?

Thanks,

Bill

Maybe they don't use existing libraries. Maybe they just calculate amortization scheduled based on formulas that can be easily implemented in C/C++/Objective-C.