/// Assigns new values to the parameters.
/// This method assumes that the parameters have been already checked.
public void DefineParameters(double shape, double scale)
{
_alpha = shape;
_beta = scale;
_norm = Math.Log(_beta) * _alpha + GammaFunction.LogGamma(_alpha);
if (_alpha < 1)
{
_b = (Math.E + _alpha) / Math.E;
}
else if (_alpha > 1)
{
_a = Math.Sqrt(2 * _alpha - 1);
_b = _alpha - Math.Log(4.0);
_q = _alpha + 1 / _a;
_d = 1 + Math.Log(4.5);
}
_incompleteGammaFunction = null;
}
/// Returns the probability of finding a random variable smaller
/// than or equal to x.
/// @return integral of the probability density function from 0 to x.
/// @param x double upper limit of integral.
public override double DistributionValue(double x)
{
return(IncompleteGammaFunction.Value(x / _beta));
}
/// Assigns new values to the parameters.
/// This method assumes that the parameters have been already checked.
public void DefineParameters(double shape, double scale)
{
_alpha = shape;
_beta = scale;
_norm = System.Math.Log(_beta) * _alpha + GammaFunction.LogGamma(_alpha);
if (_alpha < 1)
_b = (System.Math.E + _alpha) / System.Math.E;
else if (_alpha > 1)
{
_a = System.Math.Sqrt(2 * _alpha - 1);
_b = _alpha - System.Math.Log(4.0);
_q = _alpha + 1 / _a;
_d = 1 + System.Math.Log(4.5);
}
_incompleteGammaFunction = null;
}
