question: static double mypdf ( double value , double shape , double scale ) { return Math . exp ( ( shape - 1 ) * Math . log ( value ) - value / scale - GammaFunction . logGamma ( shape ) - shape * Math . log ( scale ) ) ; }
target:  This test stochastically draws gamma variates and compares the coded pdf  with the actual pdf.   The tolerance is required to be at most 1e-10.