org.hipparchus.util

Class CombinatoricsUtils.FactorialLog

java.lang.Object

org.hipparchus.util.CombinatoricsUtils.FactorialLog

Enclosing class:

CombinatoricsUtils

public static final class CombinatoricsUtils.FactorialLog
extends Object

Class for computing the natural logarithm of the factorial of n. It allows to allocate a cache of precomputed values. In case of cache miss, computation is preformed by a call to Gamma.logGamma(double).

Method Summary

Modifier and Type	Method and Description
static CombinatoricsUtils.FactorialLog	create() Creates an instance with no precomputed values.
double	value(int n) Computes log(n!).
CombinatoricsUtils.FactorialLog	withCache(int cacheSize) Creates an instance with the specified cache size.

Methods inherited from class java.lang.Object

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

Method Detail

create

public static CombinatoricsUtils.FactorialLog create()

Creates an instance with no precomputed values.

Returns:

instance with no precomputed values

withCache

public CombinatoricsUtils.FactorialLog withCache(int cacheSize)

Creates an instance with the specified cache size.

Parameters:

cacheSize - Number of precomputed values of the function.

Returns:

a new instance where cacheSize values have been precomputed.

Throws:

MathIllegalArgumentException - if n < 0.

value

public double value(int n)

Computes log(n!).

Parameters:

n - Argument.

Returns:

log(n!).

Throws:

MathIllegalArgumentException - if n < 0.