FactorialDouble (Apache Commons Numbers Combinatorics 1.0 API)

java.lang.Object
- org.apache.commons.numbers.combinatorics.FactorialDouble

```
public final class FactorialDouble
extends Object
```
Class for computing the natural logarithm of the factorial of a number. It allows to allocate a cache of precomputed values.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`static FactorialDouble`	`create()`	Creates an instance with no precomputed values.
`double`	`value(int n)`	Computes the factorial of `n`.
`FactorialDouble`	`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 FactorialDouble create()
```
    Creates an instance with no precomputed values.
    
    Returns:
    
    instance with no precomputed values
  - withCache
```
public FactorialDouble 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:
    
    IllegalArgumentException - if cacheSize < 0.
  - value
```
public double value(int n)
```
    Computes the factorial of n. The result should be small enough to fit into a double: The largest n for which n! does not exceed Double.MAX_VALUE is 170. Double.POSITIVE_INFINITY is returned for n > 170.
    
    Parameters:
    
    n - Argument.
    
    Returns:
    
    n!
    
    Throws:
    
    IllegalArgumentException - if n < 0.