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java.lang.Objectorg.apache.commons.math.special.Gamma
public class Gamma
This is a utility class that provides computation methods related to the Gamma family of functions.
Field Summary | |
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private static double |
DEFAULT_EPSILON
Maximum allowed numerical error. |
private static double |
HALF_LOG_2_PI
Avoid repeated computation of log of 2 PI in logGamma |
private static double[] |
lanczos
Lanczos coefficients |
private static long |
serialVersionUID
Serializable version identifier |
Constructor Summary | |
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private |
Gamma()
Default constructor. |
Method Summary | |
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static double |
logGamma(double x)
Returns the natural logarithm of the gamma function Γ(x). |
static double |
regularizedGammaP(double a,
double x)
Returns the regularized gamma function P(a, x). |
static double |
regularizedGammaP(double a,
double x,
double epsilon,
int maxIterations)
Returns the regularized gamma function P(a, x). |
static double |
regularizedGammaQ(double a,
double x)
Returns the regularized gamma function Q(a, x) = 1 - P(a, x). |
static double |
regularizedGammaQ(double a,
double x,
double epsilon,
int maxIterations)
Returns the regularized gamma function Q(a, x) = 1 - P(a, x). |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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private static final long serialVersionUID
private static final double DEFAULT_EPSILON
private static double[] lanczos
private static final double HALF_LOG_2_PI
Constructor Detail |
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private Gamma()
Method Detail |
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public static double logGamma(double x)
x
- the value.
public static double regularizedGammaP(double a, double x) throws MathException
a
- the a parameter.x
- the value.
MathException
- if the algorithm fails to converge.public static double regularizedGammaP(double a, double x, double epsilon, int maxIterations) throws MathException
a
- the a parameter.x
- the value.epsilon
- When the absolute value of the nth item in the
series is less than epsilon the approximation ceases
to calculate further elements in the series.maxIterations
- Maximum number of "iterations" to complete.
MathException
- if the algorithm fails to converge.public static double regularizedGammaQ(double a, double x) throws MathException
a
- the a parameter.x
- the value.
MathException
- if the algorithm fails to converge.public static double regularizedGammaQ(double a, double x, double epsilon, int maxIterations) throws MathException
a
- the a parameter.x
- the value.epsilon
- When the absolute value of the nth item in the
series is less than epsilon the approximation ceases
to calculate further elements in the series.maxIterations
- Maximum number of "iterations" to complete.
MathException
- if the algorithm fails to converge.
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