Re: Chi-square

Ib wrote:
> I have tried to graph the Chi-square cumulative distribution function.
> 
> My input is
> f(x)=integrate((1/2)^(f/2)/gamma(f/2)*x^(f/2-1)*e^(-x/2),0,x)
> where f is a ”brugerdefineret funktion…”
> It works fine when f>1, but not when f=1.
> I think the problem is x^(f/2-1) when f/2-1 is negative. 

Yes, you cannot raise 0 to a negative power. That would be the same as 
dividing by zero.

> It doesn’t help to 
> change the lower limit to 0.001.

It seems to work fine when I change the lower limit of integrate to 
0.001. But I don't think this makes much sense as the result will vary 
heavily depending on the lower value.

Best regards
Ivan Johansen

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