Converting a 2D Array Matrix into an identity matrix c#

Question

I am supposed to create a button that will convert an already existing 2D array matrix into an identity matrix. Obviously you need to make sure the amount of columns and rows are the same in the original matrix in order to make it an identity matrix but I'm a little confused on how to go about doing this.

So far, I have:

        private void btnMakeBIdentity_Click(object sender, EventArgs e)
    {
        double[,] identityMatrixB = new double[matrixBRows, matrixBCols];
        if(matrixBRows == matrixBCols)
        {
            identityMatrixB = IdentityMatrix(matrixBRows);
        }
        matrixB = identityMatrixB;

        matrixToString(matrixB, txtFullMatrixB);
    }

And the method matrixToString:

        private double[,] IdentityMatrix(int n)
     {
        double[,] result = createMatrix(n, n);
        for (int i = 0; i < n; ++i)
            result[i,i] = 1.0;
        return result;
     }

In this code: matrixB, matrixBRows, matrixBCols are all global variables of the class. Matrix B was created using:

        private void btnCreateMatrixB_Click(object sender, EventArgs e)
    {
        try
        {
            matrixBRows = Convert.ToInt32(txtMatrixBRows.Text);
            matrixBCols = Convert.ToInt32(txtMatrixBCols.Text);

        }
        catch (Exception ex)
        {
            MessageBox.Show("Please check the textboxes for Matrix B's rows and columns. Be sure you are inputing a valid integer.");
        }

        matrixB = createMatrix(matrixBRows, matrixBCols);
        matrixToString(matrixB, txtFullMatrixB);


    }

An example of output that is given after Matrix B created would be:

8.3   10   5.2   
0.1   6.3   7.8   
7.6   1.3   1.1

after running IdentityMatrix after clicking "Make Matrix B Identity" I get:

1.0   10   5.2   
0.1   1.0   7.8   
7.6   1.3   1.0

Any help or suggestions would be awesome. Thanks!

mewh · Accepted Answer · 2016-10-05 12:46:19Z

4

You have to set the other elements to 0. So you could do something like this:

for (int i = 0; i < n; ++i) {
    for (int j = 0; j < n; ++j) {
        if (i == j)
            result[i,j] = 1.0;
        else result[i,j] = 0.0;
    }
}

answered Oct 5, 2016 at 12:46

mewh

764 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Shayd3 Over a year ago

Literally as soon as I uploaded this question, I had this idea... Thank you!

Collectives™ on Stack Overflow

Converting a 2D Array Matrix into an identity matrix c#

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related