Re: HP 50g Takes hours to compute a convergent series Message #2 Posted by Joe Horn on 10 May 2013, 6:07 a.m., in response to message #1 by Matthew Richards
Integration, not summation, is controlled by the display mode. Setting FIX to something small will not change how fast a sum is computed. Furthermore, in approximate mode, the Greek Sigma function doesn't do any kind of mathematical simplification or thinking at all; it just loops from a to b and adds all the terms together. If flag 21 is clear and flag 22 is set, then a summation from 1 to to infinity will take an infinite amount of time.
In other words, Don't Do That. If you want the 50g to do any kind of symbolic simplification, you must be in exact mode. Otherwise it'll just crank it numerically by brute force looping, which is great for summations that exact mode doesn't know how to simplify. Need an approximate summation to infinity that can't be simplified? Then instead of using infinity, just use a number that's large enough to get a useful answer but not so large that it takes too long. Infinity never makes sense in approximate mode.
Hope that helps!
