class to hold main method for hall experiment

Hall.java

import java.io.*;
import java.util.*;

public class Hall{


    public static void main (String[] args) throws IOException {


        if(args.length>0){

            BufferedReader xReader=new BufferedReader(new FileReader(IOUtil.fileName(args[0])));
            BufferedReader yReader=new BufferedReader(new FileReader(IOUtil.fileName(args[1])));

            PrintWriter xyWriter = new PrintWriter(new FileWriter(args[2]));
            GNUPlot  gnuPlot = new GNUPlot();

            PrintWriter residualWriter = new PrintWriter(new FileWriter(args[3]));

            Scanner xScan = new Scanner(xReader);
            Scanner yScan = new Scanner(yReader);

            String type = xScan.nextLine();
            double field =IOUtil.skipToDouble(xScan);
            double fieldError =IOUtil.skipToDouble(xScan);

            gnuPlot.printGradient(xScan,yScan);
            double[] residual = gnuPlot.computeResidual();


            xyError(xyWriter, gnuPlot.getX(),gnuPlot.getY(),errorCurrent(gnuPlot.getX()),errorVoltage(gnuPlot.getY()));
            xyWriter.close();

            xyError(residualWriter, gnuPlot.getX(), residual,errorCurrent(gnuPlot.getX()),error(gnuPlot.getY(),gnuPlot.rss()));
            residualWriter.close();

            printHallCoefficient(printNoDensity(gnuPlot.getGradient(),field,gnuPlot, fieldError, type));
        }
    }
    public static void xyError(PrintWriter outFile, double[] x, double[] y, double[] xErr, double[] yErr ){
        for (int i=0;i<y.length;i++) {
            outFile.printf("%g %g %g %g \n", x[i], y[i],xErr[i],yErr[i]);
            System.out.printf("%g %g %g %g \n", x[i], y[i],xErr[i],yErr[i]);
        }
    }
    public static double[] errorVoltage(double[] y){
        double[] error = new double[y.length];
        for (int i=0;i<y.length;i++)
            error[i]= 0.005* y[i];
        return error;
    }


    public static double[] errorResistance(double[] y){
        double[] error = new double[y.length];
        for (int i=0;i<y.length;i++)
            error[i]=(0.009* y[i]);
        return error;
    }

    public static double[] errorCurrent(double[] x){
        double[] error = new double[x.length];
        for (int i=0;i<x.length;i++)
            error[i] =  0.01+(0.01 *  x[i]);
        return error;
    }
    public static double[] error(double[] dat, double conf){
        double[] error = new double[dat.length];
        for (int i=0;i<dat.length;i++)
            error[i] =  conf *  dat[i];
        return error;
    }

    private static double relativeError(double error, double value){
        return Math.pow(error/value,2);
    }

    private static double printNoDensity(double gradient, double field, GNUPlot gnu, double fieldError, String type){

        double electron = 1.6022 * Math.pow(10,-19);
        double numberDensity = field / ((gradient) * electron);
        System.out.printf(" %s Germanium with a magnetic flux density of of $%gmT$\n",type, field);
        System.out.printf(" Flux density has an error of $%gmT$", fieldError);
        System.out.printf(" The number density of the sample is $%g m^3/C$\n Gradient is %g \n", numberDensity, gradient);
        double errorNumberDensity=  Math.sqrt(relativeError(gnu.getGradientError(),gradient)+relativeError(fieldError,field));
        System.out.printf(" Number density has a relative error of %g m^3/C", errorNumberDensity);

        return numberDensity;
    }
    private static void printHallCoefficient(double numberDensity){

        double electron = 1.6022 * Math.pow(10,-19);
        double hallCoefficient = 1/(electron * numberDensity);
        System.out.printf("\n Hall Coefficient is %g", hallCoefficient);
    }

}