//Program to calculate the square root of a number using the Newton-Raphson.
//It stops when the difference between consecutive approximations is less than 0.00005
//by www.neiljohan.com

import java.io.IOException;


public class NewtonRaphsonClass implements NewtonInterface
{
    private static boolean debugging = true;
    private double SquareRoot;
    
/** @param tFactorial the value from which to find the square root
*  precondition tFactorial>0
*  @return x1 so that x1>0 */

    public NewtonRaphsonClass(double tFactorial) throws IOException
        {
            double x1=0;
            double x0=tFactorial/2;
            double a=tFactorial;
            boolean finished=false;

	/* check pre-condition */
	if (debugging && (tFactorial<=0)){
		System.out.println("Pre-condition violoated");
		finished=true;
	}

            while (finished==false)
            {
                x1=(x0+(a/x0))/2;

                if (x1>x0){
                    if ((x1-x0)<0.00005){
                        finished=true;
                    }
                }
                else if (x0>x1){
                    if ((x0-x1)<0.00005){
                        finished=true;
                    }
                }
                x0=x1; 
            }

		/* check post-condition */
		if (debugging && (x1<=0)){
			System.out.println("Post-condition violoated");
		}	

            SquareRoot =  x1;
        }


    public double getNewton()
        {
            return SquareRoot;
        }
}