[Free42] root finder
06-15-2016, 12:23 AM (This post was last modified: 06-15-2016 07:14 PM by Marcio.)
Post: #1
 Marcio Senior Member Posts: 438 Joined: Feb 2015
[Free42] root finder
I have been playing with the Free42 app lately and must say it's of superb quality. The option to change GUI is also top-notch.

Anyway, while programming it to find zeros of equations, I noticed something interesting:

On page 184 of the 15C's user guide, one can find the following equation:
$h = 5000\left(1-e^{-t/20}\right)-200t$
which is solved for $$t$$ when $$h=0$$. The 15C manual recommends 5 and 6 as initial estimates. In fact, if the estimates are smaller than 4, it will converge to zero (which is also correct), and that was when I suspected Free42's solver was keeping some sort of cache. No matter what other values I entered for $$t$$, the app wouldn't find the the root for $$t>0$$, which is 9.2843...

A work-around is to integrate the function (ie the program), which somehow clears the "cache", and then solve for $$t$$ again.

Is this a feature or an oddity/bug? Or did I miss something?

Thanks.
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 Messages In This Thread [Free42] root finder - Marcio - 06-15-2016 12:23 AM RE: [Free42] root solving - Gerson W. Barbosa - 06-15-2016, 01:31 AM RE: [Free42] root finder - Dieter - 06-15-2016, 10:09 PM RE: [Free42] root solving - Dieter - 06-15-2016, 01:03 PM RE: [Free42] root solving - Marcio - 06-15-2016, 01:39 PM RE: [Free42] root solving - Dieter - 06-15-2016, 07:18 PM RE: [Free42] root finder - Marcio - 06-15-2016, 09:12 PM RE: [Free42] root finder - Dieter - 06-15-2016, 10:04 PM RE: [Free42] root finder - Marcio - 06-16-2016, 03:04 PM RE: [Free42] root finder - Dieter - 06-16-2016, 05:14 PM RE: [Free42] root finder - Marcio - 06-16-2016, 06:41 PM RE: [Free42] root finder - Thomas Okken - 06-19-2016, 11:18 PM

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