FNF_chi2returns the value of the probability density function of the univariate chi-squared (χ²) distribution with parameternatx. This density,f(x;n), is defined by the expression
Xis often written as X²; among other uses, this notation emphasizes the fact that this distribution is only nonzero for values ofx0. Althoughfis sometimes defined forn< 0, most implementations, including this one, restrictfto being defined forn0.
f(x;n)
Errors
FNF_chi2causes an HTBasic error if its arguments are not of the types listed in the usage section, above, or ifnis negative.