de.unihalle.informatik.MiToBo.math

Class LogFaculty

java.lang.Object

de.unihalle.informatik.MiToBo.math.LogFaculty

public class LogFaculty
extends Object

Class to compute the logarithm of the faculty of an integer n. This class stores all values from log(0!) to log(n_max!) to provide fast access for values of n in the range [0,n_max]. If values for n > n_max are requested, the internal array is extended and n_max := n.

Author:

Oliver Gress

Field Summary

Fields

Modifier and Type	Field and Description
private double[]	logfac array to store log(0!)

Constructor Summary

Constructors

Constructor and Description
LogFaculty(int n_max) Constructor to precompute log(0!)

Method Summary

Modifier and Type	Method and Description
double	getLogFaculty(int n) log(n!)
double	getLogFacultyFraction(int n1, int n2) log(n1!
int	getMaxN()

Methods inherited from class java.lang.Object

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

Field Detail

logfac

private double[] logfac

array to store log(0!) to log(n!)

Constructor Detail

LogFaculty

public LogFaculty(int n_max)

Constructor to precompute log(0!) to log(n_max!)

Parameters:

n_max -

Method Detail

getLogFaculty

public double getLogFaculty(int n)

log(n!)

Parameters:

n -

Returns:

getLogFacultyFraction

public double getLogFacultyFraction(int n1,
                                    int n2)

log(n1! / n2!)

Parameters:

n1 - nominator faculty

n2 - denominator faculty

Returns:

log of n1!/n2!

getMaxN

public int getMaxN()