Finance App TVM with irregular cash flows
05-24-2021, 05:36 PM
Post: #1
 Stefan Falk Junior Member Posts: 10 Joined: May 2021
Finance App TVM with irregular cash flows
Hello everybody!

I am still in the process of learning the HP Prime with its overwhelming set of functionality. Up to now, I could not figure out how to calculate the loan for a bought house with additional payments. The finance app calculates well using just the monthly paid amount, but how do I calculate the plan if we pay additional amounts at different times (we are allowed to pay up to additional 5% of the total amount each year)?

Best Regards,
Stefan
05-26-2021, 01:20 AM
Post: #2
 roadrunner Senior Member Posts: 429 Joined: Jun 2015
RE: Finance App TVM with irregular cash flows
I would do something like that with the spreadsheet app; like the one attached.

05-26-2021, 06:55 AM
Post: #3
 Stefan Falk Junior Member Posts: 10 Joined: May 2021
RE: Finance App TVM with irregular cash flows

I'll try to get the hpapp into my prime.

Btw, do I remember correctly that the good old HP-92 desktop calculator could handle that, or was that "just" irregular cash flows in bond calculations?

Thanks again,
Stefan
05-26-2021, 07:06 AM
Post: #4
 Stefan Falk Junior Member Posts: 10 Joined: May 2021
RE: Finance App TVM with irregular cash flows

I tried your app and it seems to work fine. I had made an Excel sheet for the calculations, because the dates at which we paid the additional 5% varied from year to year.

Isn't there some built-in function accepting some array of dates and amounts in addition to the usual suspects such as PV, FW and so on? I could not find one yet.

Best Regards,
Stefan
05-26-2021, 11:20 AM
Post: #5
 Albert Chan Senior Member Posts: 2,142 Joined: Jul 2018
RE: Finance App TVM with irregular cash flows
Hi, Stefan Falk

Welcome to the forum.

We could do it all in finance app, by pulling all extra payments into NPV

All we need is terms and rate, and the list of extra payments.
Example, loan is 5% APY, compounded monthly, terms is 30 years (N=360)

At N=2, extra payment of $1000 At N=20, extra payment of$2000

Finance app: I%YR=5, P/Yr=12, C/Yr=12, End=√, PMT=0

// shift N=20 payments to N=2
N=18, FV=2000 → PV=−1855.7761122

// shift N=2 payments to N=0, i.e. NPV
N=2, FV=1000-(−1855.7761122) → PV=−2832.12589423

// Spread NPV effect to regular payments
N=360, FV=0 → PMT=15.2034641912
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