>>The routine / function needs to take into account the down payment, points, interest rates and adjustable mortgages.
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>>Any help is welcomed.
>
>Did you play with PV,FV,PAYMENT functions?
Yes, but the local expert determine that the functions did not accurately calculate the Internal Rate of Return (another more defined APR) therefore I could not use the provided functions.

I even tried to do a DDE to Excel but again the formula used does not give a true APR