RE: RPG math -- RPG400-L

Shoot, many moons ago, I was looking for a more accurate program to
calculate loans. I called of friend of mine, who was the D/P Manager of a
Savings & Loan in the same New Mexico town who also used a S/34, and asked
him where I could get one. His reply? "Heck, don't you have FUNLIB?
That's what we use."

Jerry C. Adams
IBM i Programmer/Analyst
Now ride off in all directions. - Michael Curtiz, directing Gary Cooper
--
A&K Wholesale
Murfreesboro, TN
615-867-5070

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx]
On Behalf Of Nathan Andelin
Sent: Thursday, April 12, 2012 11:25 AM
To: RPG programming on the IBM i / System i
Subject: Re: RPG math

Banks and credit unions have been using RPG to calculate loan-payment and
loan-remaining values since the 70's, at least; even before there was a
"power" operator **. The last calculations I wrote (years ago) used packed
decimal variables with 15,9 precision, then finally rounded with half-adjust
to 2 decimal positions.

-Nathan

----- Original Message -----
From: Dave <dfx1@xxxxxxxxxxxxxx>
To: RPG programming on the IBM i / System i <rpg400-l@xxxxxxxxxxxx>
Cc:
Sent: Thursday, April 12, 2012 4:55 AM
Subject: RPG math

Hi all,

I recently asked how to access an EXCEL formula from an RPG program but here
I am now having to reproduce the EXCEL PMT function in RPG.
Maybe someone has already done this?
Anyway, I've been given a formula to code and an EXCEL spreadsheet to
control my results.

Which I've coded like this :

MonthlyRate = interestRate /12;
MonthlyPayment = ( LoanAmount / MonthlyRate ) * ( 1 - ( 1 +
MonthlyRate ) ** ( -1 * numberOfPayments ));

LoanRemaining =
12 * MonthlyPayment *
1 - ( 1 + MonthlyRate ) ** ( -1 * numberOfPayments -
numberOfPaymentsMade ) /interestRate ;

My fields are defined so (imposed) :

LoanAmount, MonthlyPayment, LoanRemaining 13S2 numberOfPayments,
numberOfPaymentsMade 3 I 0

I've very little experience with RPG math and I'm worried about errors from
intermediate calculations How should I define the rates MonthlyRate and
interestRate so I don't get any loss of information after the divisions?

Thanks.
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