"Stef C" wrote in message ...
Hi,

I am using the ChiInv function of Excel and get an error
1004 when sending some values, but no error sending other
values... it do not seem to be an error from a certain
value (ex: start bugging when sending a value of 512 or
more...) it seem to be random, but I know that it is
not... anybody know this one.

I suspect the seemingly quirky behaviour is due to convergence
problems, although, according to the help information, it should
return N/A if it doesn't converge within 100 iterations.

You are more than welcome to use the code in
http://members.aol.com/iandjmsmith/Examples.xls.

The functions associated with the gamma distribution (also used for
the poisson, chi-squared...) have been extensively tested for shape
parameters in the range 1e-12 to 1e7 and for probabilities from
0.999999999999999 to 3e-308. Testing for this was done independently
(and unknown to me at the time) by Jerry W. Lewis and I'm indebted to
him for all his efforts. I'm glad to say Jerry has since recommended
the code and also made several suggestions to improve the code.

Ian Smith