Questionable Assignment...

Question

Public Matrix add(Matrix theM){
//implement the method such that it adds an object of matrix of the same size to
//m
//returns the result as an object of Matrix.
I dont know what that means...
* Write a description of class Matrix here.
* Kenneth Waters
* Lab05
* 3/20/2005
import java.io.*;
import java.util.*;
public class Matrix
    private double[][] m;
    private int rowN;
    private int colN;
    public Matrix(double[][] aM)
        rowN = aM.length;
        colN = aM[0].length;
        m = new double[rowN][colN];
        m = aM;
    public Matrix(String filePathName, int rows, int cols)
        int row = 0;
        m = new double[rows][cols];
        try
          Scanner s1 = new Scanner (new File(filePathName));
            while (s1.hasNextLine())
                int col = 0;
                String input = s1.nextLine();
                StringTokenizer tokenizer = new StringTokenizer( input );
            while( tokenizer.hasMoreTokens() )
                String value = tokenizer.nextToken();
                double parseValue = Double.parseDouble(value);
                m[row][col] = parseValue;
                col++;
            row++;
            catch(FileNotFoundException e)
           e.printStackTrace();
    public void display()
        for (int row = 0; row < m.length; row++ )
            for (int column = 0; column < m[ row ].length; column++)
            System.out.printf( "%.2f ", m[row][column] );
            System.out.println();
    public int getRowNumber(){
        return rowN;
    public int getColNumber(){
        return colN;
    public double getElement(int row, int col){
        return m[row][col];
    public double[] getRow(int row){
        return m[row];
    public double[] getCol(int col)
        double[] res  = new double[ rowN ];
        for(int i = 0; i < rowN; i++)
            res[i] = m[i][col];
            return res;
    public double getMax(){
        double largest = 0.0;
        for (int row = 0; row < m.length; row++ )
            for (int column = 0; column < m[ row ].length; column++)
            if( m[row][column] > largest ){
                largest = m[row][column];
        return largest;
    public double getRowSum(int rowNumber){
        double sum = 0.0;
        for(int c = 0; c < colN; c++)
            sum = sum + m[rowNumber][c];
            return sum;
    public double[] getRowSums(){
            double[] sums = new double[colN];
            for(int r=0; r < rowN; r++)
                sums[r] = getRowSum(r);
            return sums;
    public double getColSum(int colNumber)
        double sum = 0.0;
        double[] res  = new double[ colN ];
        for(int i = 0; i < rowN; i++)
            res[i] = m[i][colNumber];
            sum += res;
return sum;
public double[] getColSums()
double[] sums = new double[rowN];
for (int i = 0; i < colN; i++)
sums[i] = getColSum(i);
return sums;
public Matrix multiply(double aNumber){
double[][] s = new double[rowN][colN];
for(int r = 0; r < rowN; r++)
for(int c = 0; c < colN; c++)
s[r][c] = aNumber*m[r][c];
return new Matrix(s);
public Matrix add(Matrix theM){
That method is one of the last i have to implement. I left it open at the end so you know wher ein the code it is. I dont expect anyone to do it, just help me determine what im doing exactly, lol. Thanks

Answer 1

* Write a description of class Matrix here.
* Kenneth Waters
* Lab05
* 3/20/2005
import java.io.*;
import java.util.*;
public class Matrix
    private double[][] m;
    private int rowN;
    private int colN;
    public Matrix(double[][] aM)
        rowN = aM.length;
        colN = aM[0].length;
        m = new double[rowN][colN];
        m = aM;
    public Matrix(String filePathName, int rows, int cols)
        int row = 0;
        m = new double[rows][cols];
        try
          Scanner s1 = new Scanner (new File(filePathName));
            while (s1.hasNextLine())
                int col = 0;
                String input = s1.nextLine();
                StringTokenizer tokenizer = new StringTokenizer( input );
            while( tokenizer.hasMoreTokens() )
                String value = tokenizer.nextToken();
                double parseValue = Double.parseDouble(value);
                m[row][col] = parseValue;
                col++;
            row++;
            catch(FileNotFoundException e)
           e.printStackTrace();
    public void display()
        for (int row = 0; row < m.length; row++ )
            for (int column = 0; column < m[ row ].length; column++)
            System.out.printf( "%.2f ", m[row][column] );
            System.out.println();
    public int getRowNumber(){
        return rowN;
    public int getColNumber(){
        return colN;
    public double getElement(int row, int col){
        return m[row][col];
    public double[] getRow(int row){
        System.out.println(m[row]);
        return m[row];
    public double[] getCol(int col)
        double[] res  = new double[ rowN ];
        for(int i = 0; i < rowN; i++)
            res[i] = m[i][col];
            System.out.println(res);
            return res;
    public double getMax(){
        double largest = 0.0;
        for (int row = 0; row < m.length; row++ )
            for (int column = 0; column < m[ row ].length; column++)
            if( m[row][column] > largest ){
                largest = m[row][column];
        return largest;
    public double getRowSum(int rowNumber){
        double sum = 0.0;
        for(int c = 0; c < colN; c++)
            sum = sum + m[rowNumber][c];
            return sum;
    public double[] getRowSums(){
            double[] sums = new double[colN];
            for(int r=0; r < rowN; r++)
                sums[r] = getRowSum(r);
            return sums;
    public double getColSum(int colNumber)
        double sum = 0.0;
        double[] res  = new double[ colN ];
        for(int i = 0; i < rowN; i++)
            res[i] = m[i][colNumber];
            sum += res;
return sum;
public double[] getColSums()
double[] sums = new double[rowN];
for (int i = 0; i < colN; i++)
sums[i] = getColSum(i);
return sums;
public Matrix multiply(double aNumber){
double[][] s = new double[rowN][colN];
for(int r = 0; r < rowN; r++)
for(int c = 0; c < colN; c++)
s[r][c] = aNumber*m[r][c];
return new Matrix(s);
public Matrix add(Matrix theM){
Matrix result = new Matrix(m);
for (int row = 0; row < m.length; row++ )
for (int column = 0; column < m[ row ].length; column++)
result.m[row][column] = m[row][column] + theM.m[row][column];
return result;
public Matrix multiply(Matrix theM){
Matrix result = new Matrix(m);
for (int row = 0; row < m.length; row++ )
for (int column = 0; column < m[ row ].length; column++)
result.m[row][column] = m[row][column] * theM.m[row][column];
return result;
* Write a description of class TestMatrix here.
* @author (your name)
* @version (a version number or a date)
public class TestMatrix
    public static void main(String[] s)
        double[][] a = { {2.0,3.25,4.1},{0,1.75,5.2}};
        double[][] a1 = { {2.9,4.1,6.8},{10.12345,0.55,-5}};
        Matrix m = new Matrix(a);
        Matrix m1 = new Matrix(a1);
        System.out.println("The matrix m is ");
        m.display();    //display method tested
        System.out.println("The first row is ");
        m.getRow(0);    //displayRow method tested
        System.out.println("The first column is ");
        m.getCol(0);    //displayCol method tested
  //test getElement, getRowNumber, and getColNumber methods
        double store = m.getElement(m.getRowNumber()-1,m.getColNumber()-1);
        System.out.println("The last element is "+store);
  //test getRowSum and getRowSums methods
        System.out.println("The row sums are");
        for (int r=0; r < m.getRowNumber(); r++)
            System.out.println(""+(m.getRowSums())[r]); //calling getRowSums method
            //or System.out.println(""+m.getRowSum(r)); by calling getRowSum method
       //test add method
  System.out.println("the sum of ");
        m.display();
        System.out.println("and ");
        m1.display();
        System.out.println("is ");
        (m.add(m1)).display();
        //test multiply method
  System.out.println("the product of ");
        m.display();
        System.out.println("and ");
        m1.display();
        System.out.println("is ");
        (m.multiply(m1)).display();
        //add other codes to test each of the rest methods