Vector.java in pgm

Vector.java

public class Vector

{

   private final int N;        

   private double[] data;    

   public Vector(int N)

   {

        this.N = N;

        this.data = new double[N];

    }

                     public Vector(double[] data)

{

        N = data.length;

        this.data = new double[N];

        for (int i = 0; i < N; i++)

        this.data[i] = data[i];

    }

     Vector x = new Vector(1.0, 2.0, 3.0, 4.0);

     Vector y = new Vector(5.0, 2.0, 4.0, 1.0);

      public Vector(double... data) {

        N = data.length;

        this.data = new double[N];

        for (int i = 0; i < N; i++)

            this.data[i] = data[i];

    }

    public int length()

    {

        return N;

    }

    public double dot(Vector that)

    {

        if (this.N != that.N) throw new RuntimeException("Dimensions don't agree");

        double sum = 0.0;

        for (int i = 0; i < N; i++)

            sum = sum + (this.data[i] * that.data[i]);

        return sum;

    }

    public double magnitude()

   {

        return Math.sqrt(this.dot(this));

    }

    public double distanceTo(Vector that)

   {

        if (this.N != that.N) throw new RuntimeException("Dimensions don't agree");

        return this.minus(that).magnitude();

    }

    public Vector plus(Vector that)

   {

        if (this.N != that.N) throw new RuntimeException("Dimensions don't agree");

        Vector c = new Vector(N);

        for (int i = 0; i < N; i++)

            c.data[i] = this.data[i] + that.data[i];

        return c;

    }

    public Vector minus(Vector that)

   {

        if (this.N != that.N) throw new RuntimeException("Dimensions don't agree");

        Vector c = new Vector(N);

        for (int i = 0; i < N; i++)

            c.data[i] = this.data[i] - that.data[i];

        return c;

    }

    public double cartesian(int i)

   {

        return data[i];

    }

    public Vector times(double factor)

   {

        Vector c = new Vector(N);

        for (int i = 0; i < N; i++)

            c.data[i] = factor * data[i];

        return c;

    }

                  public Vector direction()

                  {

        if (this.magnitude() == 0.0) throw new RuntimeException("Zero-vector has no direction");

        return this.times(1.0 / this.magnitude());

                    }

                  public String toString()

                  {

        String s = "(";

        for (int i = 0; i < N; i++)

                        {

            s += data[i];

            if (i < N-1) s+= ", ";

        }

        return s + ")";

 }

 public static void main(String[] args)

{

        double[] xdata = { 1.0, 2.0, 3.0, 4.0 };

        double[] ydata = { 5.0, 2.0, 4.0, 1.0 };

        Vector x = new Vector(xdata);

        Vector y = new Vector(ydata);

        System.out.println("x        =  " + x);

        System.out.println("y        =  " + y);

        System.out.println("x + y    =  " + x.plus(y));

        System.out.println("10x      =  " + x.times(10.0));

        System.out.println("|x|      =  " + x.magnitude());

        System.out.println("   =  " + x.dot(y));

        System.out.println("|x - y|  =  " + x.minus(y).magnitude());

    }

}