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);

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

            BufferedReader keyboard =new BufferedReader(new InputStreamReader(System.in));
            System.out.print(" Input the magnetic field in mT: ");

            double field = IOUtil.skipToDouble(new Scanner(keyboard));

            System.out.print(" Input the magnetic field error in mT: ");

            double fieldError = IOUtil.skipToDouble(new Scanner(keyboard));
            System.out.printf(" Gradient gnu %g", gnuPlot.getGradient());

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

            xyError(residualWriter, gnuPlot.getX(), residual,errorCurrent(gnuPlot.getX()),errorVoltage(gnuPlot.getY()));
            residualWriter.close();
            printNoDensity(gnuPlot.getGradient(),field,gnuPlot, fieldError);
        }
    }
    private static void printNoDensity(double gradient, double field, GNUPlot gnu, double fieldError){

        double electron = 1.60217646 * Math.pow(10,-19);

        double numberDensity = field / (gradient * electron);
System.out.printf("Number density for N-Type Germanium sample with gradient of %g = %g in a field of %g mT", gradient,numberDensity,field);
        double errorNumberDensity=  Math.sqrt(relativeError((20* Math.pow(10,-6)),Math.pow(10,-3))+relativeError(gnu.getGradientError(),gradient)+relativeError(fieldError,field));
        System.out.printf("Number density has a relative error of %g mT", errorNumberDensity);


    }
    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=1;i<y.length;i++)
            error[i]=  0.015+0.2 * y[i];
        return error;
    }

    public static double[] errorCurrent(double[] x){
        double[] error = new double[x.length];
        for (int i=1;i<x.length;i++)
            error[i] =  0.01+0.01 *  x[i];
        return error;
    }

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