Thread: Matrix multiplication!!

  1. #1
    Registered User
    Join Date
    Mar 2009

    Matrix multiplication!!

    I have created a class of 3*3 matrix. In which i have defined an operator for matrix multiplication.

    the code goes like this:
    matrix operator * (matrix m)
    matrix x;
    	for (int i=0; i<3; i++)
    		for (int j=0; j<3; j++)
    	x.array[i][j]=array[1][j] * m.array[i][1];
            x.array[i][j]=array[2][j] * m.array[i][2];
            x.array[i][j]=array[3][j] * m.array[i][3];
    return x;

    can anybuddy help me this code is wrong

  2. #2
    and the Hat of Guessing tabstop's Avatar
    Join Date
    Nov 2007
    Easy start: If you intend all of those statements to be inside a loop, you will need braces.

    You seem to have looked up matrix multiplication, but you forgot about the additions.

  3. #3
    Super Moderator VirtualAce's Avatar
    Join Date
    Aug 2001
    Here's a hint:
    result[i][j] += array [i][k] * array[k][j]
    Last edited by VirtualAce; 10-18-2009 at 04:22 PM.

  4. #4
    Algorithm Dissector iMalc's Avatar
    Join Date
    Dec 2005
    New Zealand
    Here's another important hint: Arrays start at zero. An array with three elements has valid indexes [0], [1], and [2]. You got the loops right, bt not your hard-coded indexes.
    My homepage
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  5. #5
    Registered User
    Join Date
    Jun 2008
    Check your curly brackets, your code isn't doing what you think it is doing.

    You need to put brackets after the second for statement

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