[WP-34S] Chi-Square Distribution

[Dieter]

(01-14-2014 10:07 PM)Paul Dale Wrote:  The problem I fixed added a +/- at the end if p<.5
The number coming out was correct, just with the wrong sign.

Code below. The change is to add FS? F_SMALL +/- right down at the bottom.

Thank you. But as far as I can tell the new code contains a substantial error: For p in the center (i.e. between 0,23 and 0,77) the estimate uses the code following label qf_q_mid. Then the estimate is compared with two threshold values (0,04 and 4E-9), and finally label qf_q_signfix is reached where the sign gets adjusted. But at this point X does not hold the absolute value of the estimate (R_ABSZ), but 4E-9 (!). The estimate is in Y. As far as I can tell there is a X<>Y, Roll down or RCL R_ABSZ missing.

This error must be relatively new since otherwise the Normal quantile would not be able to return exact results - the quantile algorithm uses at most two iterations, and this only works if the initial estimate is sufficiently accurate.

Or do I miss something here?

Dieter