matrix multiplication

This is a discussion on matrix multiplication within the C Programming forums, part of the General Programming Boards category; matrix multiplication I have some problems with function when using arrays, I have problem to claculate two matrix multiplication by ...

  1. #1
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    Thumbs down matrix multiplication

    matrix multiplication
    I have some problems with function when using arrays,
    I have problem to claculate two matrix multiplication by using three functions
    function1:-getting values from keyboard
    function2:multyplication.
    function3:display values.

    does any can have idea to do that
    thank you!

  2. #2
    Programming Wraith GReaper's Avatar
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    you pass a pointer of the matrix array to function1 and let it input the numbers.
    you pass two pointer of the matrices you want to mult to function2, and a third pointer as the result matrix.
    you again pass the pointer of the multiplied matrix to function3 to print it.
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    I have poor knowledge about pointers can little bit explain the answer?

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    Programming Wraith GReaper's Avatar
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    Sorry, but i'm no expert. You'd better read the site tutorials before going on.
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    In general, you have M1, an s-by-r matrix and M2 a, t-by-u matrix. The operation is defined if and only if r=t. (Definition of matrix multiplication). The dimension of the result is s-by-u. Finally, each element is an inner product of rows of M1 and columns of M2. You want a triple nested for loop of some kind:

    Code:
    for(int i = 0; i < s; i++)
    {
    	for(int j = 0; i < u; j++)
            {
                    result[i][j] = 0;
    		for(int k = 0; k < r; k++)
    			result[i][j] += m1[i][k] * m2[k][j];
            }
    }
    I can't guarantee that's what you want, but that's pretty damn close. Hopefully the rest of the forum won't skin me alive.
    Last edited by QuadraticFighte; 10-23-2010 at 12:33 PM.

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