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

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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.