Class GammaRegularizedQ

All Implemented Interfaces:
Function<Vector,Double>, BivariateRealFunction, RealScalarFunction

public class GammaRegularizedQ extends AbstractBivariateRealFunction
The Regularized Incomplete Gamma Q function is defined as: \[ Q(s,x)=\frac{\Gamma(s,x)}{\Gamma(s)}=1-P(s,x), s \geq 0, x \geq 0 \] The algorithm used for computing the regularized incomplete Gamma Q function depends on the values of s and x.
  • For \(s > 100\), Q is approximated using the Gauss-Legendre quadrature.
  • For \(x < s + 1\), Q is approximated using the Pearson's series representation.
  • Otherwise, Q is approximated using the continued fraction expression by Legendre.
The R equivalent function is pgamma. E.g., pgamma(x, s, lower=FALSE).
See Also:
  • Constructor Details

    • GammaRegularizedQ

      public GammaRegularizedQ()
  • Method Details

    • evaluate

      public double evaluate(double s, double x)
      Evaluate Q(s,x).
      s - s ≥ 0
      x - x ≥ 0