# Class GammaRegularizedPInverse

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

public class GammaRegularizedPInverse
The inverse of the Regularized Incomplete Gamma P function is defined as: $x = P^{-1}(s,u), 0 \geq u \geq 1$
• When s > 1, we use the asymptotic inversion method.
• When s <= 1, we use an approximation of P(s,x) together with a higher-order Newton like method.
In both cases, the estimated value is then improved using Halley's method, c.f., HalleyRoot.

The R equivalent function is qgamma. E.g., qgamma(u, s, lower=TRUE).

## Nested classes/interfaces inherited from interface dev.nm.analysis.function.Function

Function.EvaluationException
• ## Constructor Summary

Constructors
Constructor
Description
GammaRegularizedPInverse()

• ## Method Summary

Modifier and Type
Method
Description
double
evaluate(double s, double u)
Evaluate x = P-1(s,u).

### Methods inherited from class dev.nm.analysis.function.rn2r1.AbstractBivariateRealFunction

evaluate

### Methods inherited from class dev.nm.analysis.function.rn2r1.AbstractRealScalarFunction

dimensionOfDomain, dimensionOfRange

### Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

### Methods inherited from interface dev.nm.analysis.function.Function

dimensionOfDomain, dimensionOfRange
• ## Constructor Details

• ### GammaRegularizedPInverse

public GammaRegularizedPInverse()
• ## Method Details

• ### evaluate

public double evaluate(double s, double u)
Evaluate x = P-1(s,u).
Parameters:
s - s > 0
u - 0 ≤ u ≤ 1
Returns:
P-1(s,u)