[WP-34S] Chi-Square Distribution

[Dieter]

(01-11-2014 11:11 PM)Paul Dale Wrote:  The distribution code hasn't changed since we did all that work on it.
...
Is it possible your 34S is in one of the slow clock states?

Just to be sure I set it to FAST mode. But I do not think this is the problem - the point is that the iteration in user code runs so much faster than the XROM routine.

Maybe there's a problem with the initial guess. Could you provide the first guesses for df=20 and p = 1E-10, 0,05, 0,95 and 0,99999? Or is there a way to single-step through the routine so that I can do this myself? The initial guess should be within approx. ±10% of the final result.

Back then we also discussed a modification of the Newton iteration in that the correction term applied in each iteration should be limited to, say, ±1 or ±5%. This prevents divergence and oscillation that may otherwise occur in some cases.

Dieter