Hi all,

Working on some matrix code, I'm concerned of performance issues.

here's how it works : I've a IMatrix abstract class (with all matrices operations etc), implemented by a ColumnMatrix class.

abstract class IMatrix
{
    public int Rows {get;set;}
    public int Columns {get;set;}
    public abstract float At(int row, int column);
}

class ColumnMatrix : IMatrix
{
    private data[];

    public override float At(int row, int column)
    {
        return data[row + columns * this.Rows];
    }
}

This class is used a lot across my application, but I'm concerned with performance issues. Testing only read for a 2000000x15 matrix against a jagged array of the same size, I get 1359ms for array access agains 9234ms for matrix access :

public void TestAccess()
{
    int iterations = 10;

    int rows = 2000000;
    int columns = 15;
    ColumnMatrix matrix = new ColumnMatrix(rows, columns);
    for (int i = 0; i < rows; i++)
        for (int j = 0; j < columns; j++)
            matrix[i, j] = i + j;

    float[][] equivalentArray = matrix.ToRowsArray();

    TimeSpan totalMatrix = new TimeSpan(0);
    TimeSpan totalArray = new TimeSpan(0);

    float total = 0f;
    for (int iteration = 0; iteration < iterations; iteration++)
    {
        total = 0f;
        DateTime start = DateTime.Now;
        for (int i = 0; i < rows; i++)
            for (int j = 0; j < columns; j++)
                total = matrix.At(i, j);
        totalMatrix += (DateTime.Now - start);

        total += 1f; //Ensure total is read at least once.
        total = total > 0 ? 0f : 0f;

        start = DateTime.Now;
        for (int i = 0; i < rows; i++)
            for (int j = 0; j < columns; j++)
                total = equivalentArray[i][j];
        totalArray += (DateTime.Now - start);
    }

    if (total < 0f)
        logger.Info("Nothing here, just make sure we read total at least once.");

    logger.InfoFormat("Average time for a {0}x{1} access, matrix : {2}ms", rows, columns, totalMatrix.TotalMilliseconds);
    logger.InfoFormat("Average time for a {0}x{1} access, array : {2}ms", rows, columns, totalArray.TotalMilliseconds);
    Assert.IsTrue(true);
}

So my question : how can I make this thing faster ? Is there any way I can make my ColumnMatrix.At faster ? Cheers !