Simple matrix-vector multiplication

MatrixVectorMultiply1.cs

using System;
using System.Diagnostics;

namespace MatrixVectorMultiply
{
    class MatrixVectorMultiply1
    {
        static void Main(string[] args)
        {
            const int dim = 1024 * 8;

            var matrix = new float[dim, dim];
            var vecIn = new float[dim];
            var vecOut = new float[dim];

            Init(dim, matrix, vecIn);

            Stopwatch watch = Stopwatch.StartNew();

            for (int j = 0; j < dim; j++)
            {
                for (int i = 0; i < dim; i++)
                {
                    vecOut[j] += matrix[i, j] * vecIn[j];
                }
            }

            watch.Stop();

            Console.WriteLine("Elapsed time for example #1: " + watch.ElapsedMilliseconds + " ms");
        }

        private static void Init(int dim, float[,] matrix, float[] vecIn)
        {
            for (int i = 0; i < dim; i++)
            {
                for (int j = 0; j < dim; j++)
                {
                    matrix[i, j] = i*j;
                }
            }

            for (int i = 0; i < dim; i++)
            {
                vecIn[i] = i;
            }
        }
    }
}