# Monthly Archives: October 2009

1 post

## Fun with matrix multiplication and unsafe code

In this post I will compare two methods that perform matrix multiplication. We start by defining the Matrix class:

```class Matrix
{
public Matrix(int dim1, int dim2)
{
_matrix = new double[dim1, dim2];
}

public int Height { get { return _matrix.GetLength(0); } }
public int Width { get { return _matrix.GetLength(1); } }

public double this[int x, int y]
{
get { return _matrix[x, y]; }
set { _matrix[x, y] = value; }
}
}```

Next we add the first algorithm to the Matrix class which performs a naive multiplication:

``` public static Matrix NaiveMultiplication(Matrix m1, Matrix m2)
{
Matrix resultMatrix = new Matrix(m1.Height, m2.Width);
for (int i = 0; i < resultMatrix.Height; i++)
{
for (int j = 0; j < resultMatrix.Width; j++)
{
resultMatrix[i, j] = 0;
for (int k = 0; k < m1.Width; k++)
{
resultMatrix[i, j] += m1[i, k] * m2[k, j];
}
}
}
return resultMatrix;
}```

The second method uses unsafe code: Continue reading