dchisq(x, df) pchisq(q, df) qchisq(p, df) rchisq(n, df)
df degrees of freedom. dchisq gives the density,
pchisq gives the distribution function qchisq gives
the quantile function and rchisq generates random deviates.
The chi-square distribution with df = n degrees of freedom has density
f(x) = 1 / (2^(n/2) Gamma(n/2)) x^(n/2-1) e^(-x/2)