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41C/CV root finders
05-25-2015, 07:19 PM (This post was last modified: 05-25-2015 07:26 PM by Dieter.)
Post: #16
RE: 41C/CV root finders
(05-25-2015 05:35 AM)Ángel Martin Wrote:  Yes it is interruptible (the code checks for a key press event) but no, there is no counter due to available space restriction (it is also in the SandMath, which was very crowded already). So the example above just keeps iterating until the user stops it. Not perfect, but then... who said "the better is the enemy of the good"?

Voltaire?

(05-25-2015 05:35 AM)Ángel Martin Wrote:  As to whether there are missing terms in the formula for the derivative, well I hope not; barring a sinister transcription error that's the expression used in the code. I'll double check my notes.

I think there are some power symbols "^" missing. Both in the derivative and in the initial guess.

I assume the latter should read [abs(PV + n*PMT + FV)]1/n. For the sample case in this thread this yields an initial i of 1,65 or 165%. ?!? Also the value can never be negative. That's why I asked how you developed this formula.

BTW if space is an issue there is a very simply solution: simply set the inital i to a value very close to zero, e.g. 10–4. A value of exactly zero will not work because the standard TVM formulas divide by i, but a value very close to this would return (approximately) the estimate I posted - right after the first iteration. So all you lose is a bit of execution speed – i.e. the difference between the time required for one iteration loop and the calculation of the initial estimate. ;-)

Dieter
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Messages In This Thread
41C/CV root finders - Dave Britten - 05-20-2015, 07:07 PM
RE: 41C/CV root finders - Thomas Klemm - 05-20-2015, 07:36 PM
RE: 41C/CV root finders - Dieter - 05-20-2015, 07:44 PM
RE: 41C/CV root finders - Dave Britten - 05-20-2015, 08:08 PM
RE: 41C/CV root finders - Massimo Gnerucci - 05-20-2015, 08:40 PM
RE: 41C/CV root finders - Dave Britten - 05-20-2015, 08:49 PM
RE: 41C/CV root finders - Didier Lachieze - 05-21-2015, 11:12 AM
RE: 41C/CV root finders - Dieter - 05-21-2015, 11:40 AM
RE: 41C/CV root finders - Dave Britten - 05-21-2015, 12:51 PM
RE: 41C/CV root finders - Dieter - 05-21-2015, 07:36 PM
RE: 41C/CV root finders - Dieter - 05-22-2015, 08:34 AM
RE: 41C/CV root finders - bshoring - 05-27-2015, 10:09 PM
RE: 41C/CV root finders - Dieter - 05-27-2015, 11:16 PM
RE: 41C/CV root finders - Ángel Martin - 05-28-2015, 06:19 AM
RE: 41C/CV root finders - Dieter - 05-28-2015, 08:42 AM
RE: 41C/CV root finders - bshoring - 05-28-2015, 09:37 PM
RE: 41C/CV root finders - Ángel Martin - 05-22-2015, 01:14 PM
RE: 41C/CV root finders - Dieter - 05-22-2015, 07:07 PM
RE: 41C/CV root finders - Dieter - 05-24-2015, 07:10 PM
RE: 41C/CV root finders - Ángel Martin - 05-25-2015, 05:35 AM
RE: 41C/CV root finders - Dieter - 05-25-2015 07:19 PM
RE: 41C/CV root finders - Ángel Martin - 05-26-2015, 05:06 AM
RE: 41C/CV root finders - Dieter - 05-26-2015, 05:39 PM
RE: 41C/CV root finders - Ángel Martin - 05-26-2015, 09:26 PM
RE: 41C/CV root finders - Dieter - 05-26-2015, 10:08 PM
RE: 41C/CV root finders - rprosperi - 05-27-2015, 12:30 AM
RE: 41C/CV root finders - Dieter - 05-27-2015, 11:08 PM
RE: 41C/CV root finders - Ángel Martin - 05-28-2015, 05:44 AM
RE: 41C/CV root finders - Dieter - 05-28-2015, 09:50 PM
RE: 41C/CV root finders - Ángel Martin - 05-29-2015, 07:58 AM
RE: 41C/CV root finders - Ángel Martin - 05-27-2015, 05:17 AM
RE: 41C/CV root finders - Dieter - 05-27-2015, 01:50 PM
RE: 41C/CV root finders - Ángel Martin - 05-27-2015, 03:03 PM
RE: 41C/CV root finders - Dieter - 05-27-2015, 07:15 PM
RE: 41C/CV root finders - Dieter - 05-28-2015, 09:59 AM
RE: 41C/CV root finders - Ángel Martin - 05-28-2015, 11:27 AM
RE: 41C/CV root finders - Ángel Martin - 05-28-2015, 01:54 PM
RE: 41C/CV root finders - Dieter - 05-28-2015, 06:33 PM
RE: 41C/CV root finders - Ángel Martin - 05-29-2015, 08:04 AM
RE: 41C/CV root finders - Ángel Martin - 05-29-2015, 05:54 PM
RE: 41C/CV root finders - Dieter - 05-29-2015, 06:15 PM
RE: 41C/CV root finders - Ángel Martin - 05-29-2015, 06:44 PM
RE: 41C/CV root finders - Dieter - 05-29-2015, 07:19 PM
RE: 41C/CV root finders - Dieter - 05-30-2015, 12:37 PM
RE: 41C/CV root finders - Ángel Martin - 05-30-2015, 02:04 PM
RE: 41C/CV root finders - Dieter - 05-29-2015, 08:00 PM



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