41C/CV root finders

[Dieter]

(05-27-2015 07:15 PM)I Wrote:  I would suggest the formula at the bottom of post #13 in this thread. There you'll also find the other mathematics I use.
However, cases may exist where the denominator of i0 becomes zero. So I would do it this way:

Here's another, very simple method:

Code:

i0 = 2 / n * (PV + n*PMT + FV) / (FV – PV)

The estimate is the same for BEGIN and END mode. Here the denominator only becomes zero if FV = PV, which does not make much sense anyway. ;-)

This is a simplification of another estimate that I use for quite some time which works very well. The original formula uses (n+1) and (n–1) as the factors at PV resp. FV, while this simplified method uses n for both.

But again, there is no "golden estimate" that works well for all possible cases.

Dieter