code 41758;
real procedure CHISQDENS(X, DF);
value X, DF; real X, DF;
CHISQDENS:= if DF ≤ 0
            then STATAL3ERROR(“CHISQDENS”, 2, DF)
            else if X ≤ 0 then 0 else
            EXP((DF / 2 - 1) × LN(X) - X / 2 -
                 DF × LN(2) / 2 - LOGGAMMA(DF / 2));
eop