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  4. Adding / Multiplying two matrices

Adding / Multiplying two matrices

Scheduled Pinned Locked Moved Java
javawpftoolshelptutorial
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  • N nt_virus

    poor me... I modified as following ,, and I m done around 90%

    /*
    * To change this template, choose Tools | Templates
    * and open the template in the editor.
    */

    package javaapplication6;
    import java.io.*;
    /**
    *
    * @author Sachin
    */
    public class Main {

    /\*\*
 \* @param args the command line arguments
 \*/
public static void main(String\[\] args) throws IOException
{
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

    try{
    System.out.println("Enter number of rows");
    int m = Integer.parseInt(br.readLine());
    System.out.println("Enter number of columns");
    int n = Integer.parseInt(br.readLine());
    int[][] first = new int[m][n];
    int[][] second = new int[m][n];
    int[][] sum = new int[m][n];
    System.out.println("Enter Value of first matrix");
    {
    for (int i=0;i<first.length;i++)
    {
    System.out.println("Row no. " + (i+1));
    for (int j=0; j<first[i].length;j++)
    {
    System.out.println("Enter value for column no. " + (j+1));
    first[i][j] = Integer.parseInt(br.readLine());

            }
    }
}
System.out.println("Enter value of second matrix");
{
    for (int i=0;i<second.length;i++)
    {
        System.out.println("Row no. " + (i+1));
        for (int j=0;j<second\[i\].length;j++)
        {
            System.out.println("Enter value for column no. " + (j+1));
            second\[i\]\[j\] = Integer.parseInt(br.readLine());
        }
    }
    }
System.out.println("Sum of two matrices are:");
{
    for (int i=0;i<first.length;i++)
    {
        for (int j = 0; j<second.length;j++)
        {
            sum\[m\]\[n\] = first\[i\]\[j\] + second\[i\]\[j\];
        }
    }
    System.out.println(sum\[m\]\[n\]);
}
}
catch (IOException e)
{
   System.out.println(e);
}
}

    }

    same error is showing when i m adding two arrays.. :(

    N Offline
    N Offline
    nt_virus
    wrote on last edited by
    #7

    99% done..

    for (int i=0;i<first.length;i++)
    {
    for (int j = 0; j<second.length;j++)
    {
    sum[i][j] = first[i][j] + second[i][j];
    System.out.println(sum[i][j]);
    }

    But result are showing in vertical manner.. not like matrix way..

    L 1 Reply Last reply
    0
    • L Lost User

      nt_virus wrote:

      sum[m][n] = first[i][j] + second[i][j];

      Sorry but I stupidly missed this first time round, but you are using the wrong indices again. sum[m][n] is an array of size m by n, so the highest cell that can be addressed is sum[m-1][n-1]. Change it to sum[i][j] and I think it should work.

      N Offline
      N Offline
      nt_virus
      wrote on last edited by
      #8

      We both post posted at the same time. haha.

      1 Reply Last reply
      0
      • N nt_virus

        99% done..

        for (int i=0;i<first.length;i++)
        {
        for (int j = 0; j<second.length;j++)
        {
        sum[i][j] = first[i][j] + second[i][j];
        System.out.println(sum[i][j]);
        }

        But result are showing in vertical manner.. not like matrix way..

        L Offline
        L Offline
        Lost User
        wrote on last edited by
        #9

        nt_virus wrote:

        But result are showing in vertical manner.. not like matrix way..

        I can never remember what the order is supposed to be (I stick to one-dmensional arrays), so I'm afraid you will have to find it by trial and error. I would give you a hand but my Java system is not usable today.

        N 1 Reply Last reply
        0
        • L Lost User

          nt_virus wrote:

          But result are showing in vertical manner.. not like matrix way..

          I can never remember what the order is supposed to be (I stick to one-dmensional arrays), so I'm afraid you will have to find it by trial and error. I would give you a hand but my Java system is not usable today.

          N Offline
          N Offline
          nt_virus
          wrote on last edited by
          #10

          please do it in c# if you can, I will convert. I did my all possible things.

          L 1 Reply Last reply
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          • N nt_virus

            please do it in c# if you can, I will convert. I did my all possible things.

            L Offline
            L Offline
            Lost User
            wrote on last edited by
            #11

            OK, but it may take some time.

            N 1 Reply Last reply
            0
            • L Lost User

              OK, but it may take some time.

              N Offline
              N Offline
              nt_virus
              wrote on last edited by
              #12

              yes, no problem. do you use messenger ?

              L 1 Reply Last reply
              0
              • N nt_virus

                yes, no problem. do you use messenger ?

                L Offline
                L Offline
                Lost User
                wrote on last edited by
                #13

                OK, I got the answer in C#, so I think the Java code needs to be:

                for (int i=0;i < first.length;i++)
{
    for (int j = 0; j < first\[i\].length;j++)
    {
        sum\[i\]\[j\] = first\[i\]\[j\] + second\[i\]\[j\];
        System.out.print(sum\[i\]\[j\] + "  ");
    }
    System.out.println("");
}

                I'm not sure about the expression first.length, but basically i needs to iterate the rows, and j the columns. You also need to print each column value without the newline (print rather than println?) and then put the System.out.println(""); statement after the last column. It probably needs some tidying up to get the columns lined up, but I'm sure you will be able to manage it. No, not on messenger.

                N 1 Reply Last reply
                0
                • L Lost User

                  OK, I got the answer in C#, so I think the Java code needs to be:

                  for (int i=0;i < first.length;i++)
{
    for (int j = 0; j < first\[i\].length;j++)
    {
        sum\[i\]\[j\] = first\[i\]\[j\] + second\[i\]\[j\];
        System.out.print(sum\[i\]\[j\] + "  ");
    }
    System.out.println("");
}

                  I'm not sure about the expression first.length, but basically i needs to iterate the rows, and j the columns. You also need to print each column value without the newline (print rather than println?) and then put the System.out.println(""); statement after the last column. It probably needs some tidying up to get the columns lined up, but I'm sure you will be able to manage it. No, not on messenger.

                  N Offline
                  N Offline
                  nt_virus
                  wrote on last edited by
                  #14

                  fantastic.. It works.. you made my day (night here actually) .. Thanks a lot.

                  L 1 Reply Last reply
                  0
                  • N nt_virus

                    fantastic.. It works.. you made my day (night here actually) .. Thanks a lot.

                    L Offline
                    L Offline
                    Lost User
                    wrote on last edited by
                    #15

                    Cheers, happy to help. It also gave me some incentive to get back on Java which I haven't touched for a while. It's early evening here (UK) so are you west or east?

                    N 1 Reply Last reply
                    0
                    • L Lost User

                      Cheers, happy to help. It also gave me some incentive to get back on Java which I haven't touched for a while. It's early evening here (UK) so are you west or east?

                      N Offline
                      N Offline
                      nt_virus
                      wrote on last edited by
                      #16

                      Java is very nice. I m on east. India. +5.30

                      L 1 Reply Last reply
                      0
                      • N nt_virus

                        Java is very nice. I m on east. India. +5.30

                        L Offline
                        L Offline
                        Lost User
                        wrote on last edited by
                        #17

                        You may find this hard to believe but that's the country of my birth! I was born in Mussoorie (in the hills), my dad and my brother in Naini Tal. But my only return visit was in 2005 to Bangalore, which also was nice - at least the people.

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