(01-11-2014 01:37 PM)Sanjeev Visvanatha Wrote: Hello,
I was comparing output between HP48sx MATHLIB [Ref. 1] and WP-34S (v 3.2 3375) for some of the probability distributions. For this purpose, I was replicating the examples from the HP-21S user's manual (pg. 42-52)
I noticed that the Inverse of the Chi-Square distribution for the WP-34S does not seem (to me) to produce the same result as what is listed in the 21S manual pg. 50.
Degrees of freedom = 19
Upper tail probability = 0.001
Keystrokes on WP-34S:
19 [STO] J
0.001 [h] [PROB] [ϰ²INV]
This results in 5.4068 (in FIX4)
The 21S example on pg. 50 of its user manual gives a result of 43.8202 (function name is ϰ²p). This is also consistent with HP-48sx MATHLIB function IUTPC(19, 0.001).
For reference, the IOP for the v3.2 manual of the WP-34S indicates that ϰ²INV should be equal to ϰ²p of the 21S. Is my understanding of how to use this distribution on the WP-34S incorrect?
Thank you for any insights you may have!
[1] HP 48SX Engineering Mathematics Library, John F. Holland
5.4068 is correct for 0.1%, while 43.8202 is correct for 99.9%
Integrating form zero to p, the value returned must increase for growing p (see pp. 54f of the manual quoted). The HP-21S calculates with the error probability instead.
d:-)