Sunday Afternoon Light TVM (HP71B w/ MATH ROM)

10082017, 05:00 PM
(This post was last modified: 10082017 05:02 PM by Gerson W. Barbosa.)
Post: #1




Sunday Afternoon Light TVM (HP71B w/ MATH ROM)
The following finds i when FV = 0, given PV, PMT and n. This by no means intends to be either fast or accurate. Instead, it will get slower and slower as n increases and will lose accuracy as the ratio PV/PMT approaches 1. Anyway, for my personal needs two decimal places and n up to 3 might suffice. Exact close form solutions to this problem are possible for n up to 4, but the resulting expressions are by no means practical to be used in a light TVM program. The builtin solver might be faster regards the value of n, but I decided to see how PROOT would perform.
Code:
>RUN PV? 100 PMT? 55 N? 2 I = 6.59646009785 % (78) >RUN PV? 500 PMT? 101.51 N? 5 I = .501659795442 % (35) >RUN PV? 100 PMT? 50.01 N? 2 I = 1.33330372034E2 % (0700) >RUN PV? 3229.10 PMT? 308.25 N? 12 I = 2.15465859368 % (76) >RUN PV? 3329.10 PMT? 1849.50 N? 2 I = 7.32122812931 % I would surely be better off with an HP12C or even with RPN38 CX if I don't want to carry a calculator around :) I've found it easier to write an RPL version first on my HP 50g yesterday night, just before going to sleep. Who dare say RPL stands for RePelLent? (See, the code fits nicely in the box! :) Code:
3329.10 1849.50 2 LTVM > 7.32122812931 

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