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Thread: Sum elements column by column

  1. #1
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    Default Sum elements column by column

    Hi!
    I have to create this program, and it's working fine, but for some reason I cannot comprehend, it doesn't return doubles
    If I try to change:

    double total = 0;

    the return type is still incorrect.

    Any help will be appreciated
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~

    import java.util.Scanner;
    public class SumElementsByColumn {
    public static void main(String[] args) {
    double [][] matrix = new double[3][4];

    Scanner input = new Scanner(System.in);
    System.out.println("Enter " + matrix.length + " rows and " +
    matrix[0].length + " columns: ");
    for (int row = 0; row < matrix.length; row++){
    for ( int column = 0; column < matrix[row].length; column++){
    matrix[row][column] = input.nextDouble();
    }
    }
    sumColumn(matrix,0);
    }
    public static int sumColumn(double[][] m, int columnIndex){
    int total = 0;
    for ( int column = 0; column <= columnIndex; column++){
    total = 0;
    for (int row = 0; row < m.length; row++){
    total += m[row][column];
    }
    System.out.println(total);
    }
    return total;
    }

    }


  2. #2
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    Default Re: Sum elements column by column

    You are accumulating into an int. Total is an int, and the methods return type is int.

    In other words, change the return type to double, and the total into double.
    Last edited by theoriginalanomaly; May 8th, 2013 at 01:30 PM. Reason: Clarity

  3. #3
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    Default Re: Sum elements column by column

    Quote Originally Posted by theoriginalanomaly View Post
    You are accumulating into an int. Total is an int, and the methods return type is int.

    In other words, change the return type to double, and the total into double.


    I saw it earlier today!
    Such a silly mistake!!
    Thanks a lot though! n_n

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