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MATH: Internal Rate of Return (IRR) Formula in LUA?

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  • MATH: Internal Rate of Return (IRR) Formula in LUA?

    Internal Rate of Return (IRR) Formula in LUA?

    I am a Mortgage Banker here in the U.S., and have been for the past 22+ years, and have built many Excel Spreadsheets over the years to assist home buyers/owners to make well informed decisions when selecting a mortgage loan. I am looking to develop an AMS application that will eliminate the need of the many spreadsheets I use and consolidate them all in 1 AMS application. Although I have learned quite a bit over the years developing AMS applications for use in other areas of my business, I will humbly admit that I do need help with converting the necessary mathematical financial formulas to LUA.

    I currently have the LUA code for calculating a principal & interest payment, so I'm all set there. I am in need of the Internal Rate of Return (IRR) LUA code. This is an important piece of my application to remain compliant with Federal Regulation Z (T.I.L.A.) disclosure.

    If there are any experts out there that can provide the LUA code for IRR, it was be greatly appreciated. Thank you in advance for taking the time to read this post and help in offering a solution.

  • #2
    Here is what I found doing a Google search...

    0 = P0 + P1/(1+IRR) + P2/(1+IRR)2 + P3/(1+IRR)3 + . . . +Pn/(1+IRR)n

    Here's the link to the article:

    Anyone able to convert this to LUA?

    I am looking to use the IRR formula to calculate the A.P.R. for both Fixed Rate and Adjustable Rate Morgage (ARM) Loans. The ARM loans are a bit trickier since the interest rate adjusts after the initial fixed rate period.

    example: 5/1 ARM - 60 payments at the note rate followed by 300 payments at the fully indexed rate (index+margin)

    I will share an example .apz project once this piece is solved. Any help would be greatly appreciated.
    Last edited by David REMD; 04-13-2014, 12:26 PM.


    • #3
      Anyone to the North, South, East, West; from down under or across the pond that can help in providing the LUA Code for mortgage loan APRs and IRRs for fixed and adjustable rate mortgages. please?