float[,] y1 = new float[1, 5];
            y1[0, 0] = 5;
            y1[0, 1] = 4;
            y1[0, 2] = 3;
            y1[0, 3] = 2;
            y1[0, 4] = 1;

y1
{Dimensions:[1, 5]}
    [0, 0]: 5.0
    [0, 1]: 4.0
    [0, 2]: 3.0
    [0, 3]: 2.0
    [0, 4]: 1.0