Package com.irurueta.numerical

Class DoubleFactorialEstimator

java.lang.Object

com.irurueta.numerical.DoubleFactorialEstimator

public class DoubleFactorialEstimator
extends Object

Estimates factorial values as double precision floating point values.

Field Summary

Fields

Modifier and Type	Field	Description
private final double[]	cache	Cache of values.
static final int	CACHE_SIZE	Cache size for factorial values that can be represented without overflowing with double precision.

Constructor Summary

Constructors

Constructor	Description
DoubleFactorialEstimator()	Constructor with default cache size.
DoubleFactorialEstimator(int cacheSize)	Constructor.

Method Summary

Modifier and Type	Method	Description
double	factorial(int value)	Gets factorial of provided value represented with double precision.
int	getCacheSize()	Gets current cache size.

Methods inherited from class java.lang.Object

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

Field Details

CACHE_SIZE

public static final int CACHE_SIZE

Cache size for factorial values that can be represented without overflowing with double precision. Values up to 170! are representable, 171! overflows.

See Also:

• Constant Field Values

cache

private final double[] cache

Cache of values.

Constructor Details

DoubleFactorialEstimator

public DoubleFactorialEstimator()

Constructor with default cache size.

DoubleFactorialEstimator

public DoubleFactorialEstimator(int cacheSize)

Constructor.

Parameters:

cacheSize - size of cache.

Throws:

IllegalArgumentException - if provided value is less than 1 or exceeds 171.

Method Details

getCacheSize

public int getCacheSize()

Gets current cache size.

Returns:

cache size.

factorial

public double factorial(int value)

Gets factorial of provided value represented with double precision.

Parameters:

value - value to compute factorial for.

Returns:

computed factorial value.

Throws:

IllegalArgumentException - if provided value exceeds cache size.