private void DefineRandomGenerator()
 {
     _gamma1 = new GammaDistribution(_alpha1, 1.0);
     _gamma2 = new GammaDistribution(_alpha2, 1.0);
 }
 /// Assigns new values to the parameters.
 /// This method assumes that the parameters have been already checked.
 private void DefineParameters(double shape1, double shape2)
 {
     _alpha1 = shape1;
     _alpha2 = shape2;
     _norm = GammaFunction.LogBeta(_alpha1, _alpha2);
     _gamma1 = null;
     _gamma2 = null;
     _incompleteBetaFunction = null;
 }