41C/CV root finders

[Dieter]

(05-22-2015 01:14 PM)Ángel Martin Wrote:  Seems to hold up quite well but again thit is a MCODE implementation using the internal 13-digit precision routines from the OS.

Ángel, how does your MCODE version behave if there is no solution? Does it loop forever, did you provide an iteration counter, or what will happen? And – please excuse my dumb question – is MCODE interruptable by the user?

You may try the standard example (n=10, PV=50, PMT=–30, FV=400) with n=8 or less. In this case no solution exists.

Some time ago I tried to handle such cases in an extensive 34s program that was able to detect whether a solution exists or not (well, at least in most cases ;-)). This included finding a local extreme of the TVM function and checking for sign changes, so that even multiple solutions could be found. But covering at least the most common cases is not trivial at all, cf. earlier discussions in the old forum.

Dieter