I’m currently working on a project that happens to need a JavaScript and a PHP implementation of the Excel PMT function.  I won’t bore you with the details (but ask if you’re intrigued), but it has to do with Loan Modifications that are all the rage nowadays thanks to Obama Administration initiatives that will hopefully help Americans save their mortgages, prevent foreclosures, support real estate prices and generally speaking save the world from sure doom.

So after being handed an Excel spreadsheet that made heavy use of the PMT Excel function (and never having used said function), I proceeded to research this beast.  Let me tell you, there are lots of very confused people searching for solutions on how to implement it in various languages, trying to figure out how the function works, etc, etc, etc. I even came across some folks that think Excel / Microsoft is behind a sinister plot to undermine the world’s economy via a wrong implementation of the function.  Rest assured, I think Microsoft understands the Time Value of Money – TMV for those who still remember anything from their Finance class in college.  So I figured I’d do a little writeup of what I figured out to save somebody else the headache.

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