code 41756;
real procedure GAMMADENS(X,ALPHA, SCALE);
value X,ALPHA,SCALE; real X,ALPHA,SCALE;
if X ≤ 0 then GAMMADENS:= 0 else
begin
  if ALPHA ≤ 0
  then STATAL3 ERROR(“GAMMADENS”,2,ALPHA)
  else if SCALE ≤ 0
         then STATAL3 ERROR(“GAMMADENS”, 35,SCALE);
         
  GAMMADENS :=
    EXP(- ALPHA × LN(SCALE) - LOGGAMMA(ALPHA) -
       X / SCALE + (ALPHA - 1) × LN(X))
end GAMMADENS;
eop