Function builtin_dchisq 

fn builtin_dchisq(
    args: &[RValue],
    named: &[(String, RValue)],
) -> Result<RValue, RError>

Chi-squared density function.

The chi-squared distribution with df degrees of freedom is Gamma(df/2, 1/2), so dchisq(x, df) = dgamma(x, df/2, rate = 0.5).

@param x quantile vector @param df degrees of freedom @return numeric vector of densities