Chi2DistriQuantile
Declaration: 
Chi2DistriQuantile (p: double; df: integer): double; 
The function Chi2DistriQuantile returns the quantile value for the chisquare distribution for a given probability p and a given number of degrees of freedom df. The parameter p may take any value in the open interval (0,1). If Chi2DistriQuantile is called using an invalid value of p a value of 0.0 is returned.

Hint 1: 
The calculated value is exact to about 8 significant figures. 
Hint 2: 
The function Chi2DistriQuantile calculates the quantile by using the integral from 0.0 to the c^{2} value. This differs from the convention of how the integral of the c^{2} distribution is used in many statistical packages, which tabulate the integral between +infinite and the c^{2} value. Thus you have to use 1p to get comparable results. For example, in order to calculate the function FCHIINV(p,df) of Microsofts Excel® you have to use Chi2DistriQuantile(1p,df). 
