Maximum Liklihood Estimator for Laplace Density Function

MLE_LAPLACE.java

/*
 *  Author : JAYAPRAKASH S
 *  Maximum liklihood estimator for Laplace density function
 *  Mail : first_name [at] cse [dot] iitb [dot] ac [dot] com
 *  Please mail me, if any error is found.
 */

import java.util.ArrayList;
import java.util.Collections;


public class Main {
	/* MLE of m(Mew) and b */
	double m,b;
	/* samples drawn/taken for MLE task*/ 
	ArrayList<Double> sample = new ArrayList<Double>();
	int n;
	void calc_m(String []a)
	{
		n = a.length;
		if( n < 1 ) { 
			System.err.println("No Samples Given");
			return ;
		}
		for( int i=0;i<n;i++)
			sample.add ( Double.valueOf(a[i]) );
		Collections.sort(sample);
		if( n % 2 == 1)
			m = sample.get(n/2);
		else
		{
			/* we can take any value from sample[n-1/2] to sample[n/2] */
			// here are taking mean of two
			m = sample.get(n/2) + sample.get((n-1)/2); 
			m = m / 2;
		}
		System.out.println("Mew m = " + m);
		System.out.println("b = " + calc_b());
		System.out.println("f = " + calc_f());
	}
	public Double calc_b()
	{
		int n = sample.size();
		for( int i=0;i<n;i++)
			b = b + Math.abs(m - sample.get(i));
		b = b / n;
		return b;
	}
	public Double calc_f()
	{
		int n = sample.size();
		Double f = 1.0,t;
		for( int i=0;i<n;i++)
		{
			t = 1 / (2 * b);
			t = t  * Math.pow(Math.E, -1 * Math.abs(sample.get(i)- m) / b );
			f = f *t;
		}
		return f;
	}
	public static void main(String []a)
	{
		Main c = new Main();
		c.calc_m(a);
	}
}