MATLAB Nested For Loop and Plot Results

Hello, I'm new to MATLAB and I'm trying to have multiple overlayed plots on a single plot using nested for loop. However, my current code doesn't generate any results. Maybe I'm doing something wrong. I have Fz value ranging from 4 KN to 8 KN and the alpha value ranging from -10 to +10 degree. Appreciate your time in advance. Thanks.

a0 = 1.43E+00; a1 = -1.68E+01; a2 = -9.81E+02; a3 = -2.48E+03;
a4 = -1.15E+01; a5 = 0.00E+00; a6 = 1.90E-01; a7 = 8.16E-01;
a8 = -1.61E-02; a9 = -1.07E-01; a10 = 0.00E+00; a11 = -1.75E+01;
a12 = -7.20E+01; a13 = 0.00E+00; a14 = 0.00E+00; a15 = 0.00E+00;
a16 = 0.00E+00; a17 = 2.35E-01;

gamma = 1; 

t = -10:0.1:10;
y = zeros(500,500);

for Fz = 4:1:8
    for alpha = 1:0.1:length(t)
        s_hy = (a8*Fz) + a9 + (a10*gamma);
        s_vy = (a11*Fz) + a12 + (((a13*Fz)+a14)*(Fz*gamma));
        Cy = a0;
        Dy = ((a1*Fz^2)+(a2*Fz))*(1-(a15*gamma^2));
        Ky = a3*sind(2*atan(Fz/a4))*(1-(a5*abs(gamma)));
        By = Ky/(Cy*Dy);
        alpha_y = alpha + s_hy;
        Dummy = ((a16.*gamma)+a17)*sign(alpha_y);
        Ey = ((a6*Fz)+a7)*(1-Dummy);
        Dummy1 = Ey.*((By.*alpha_y) - (atand(By.*alpha_y)));
        Dummy2 = Cy.*atan((By.*alpha_y) - Dummy1);
        y(alpha) = -((Dy.*sin(Dummy2)) + s_vy);
    end
      hold all;
      plot(t,y,'LineWidth', 2);
end

Answer 1

[Walter Roberson]

t = -10:0.1:10;

201 elements I believe.

for alpha = 1:0.1:length(t)

That seems odd. 1:0.1:201 would be over 2000 entries. Why would you want to iterate alpha according to the number of elements in t, unless you were iterating by 1 so that alpha might index t?

        y(alpha) = -((Dy.*sin(Dummy2)) + s_vy);

alpha is not an integer, you cannot index with it.

y = zeros(500,500);

You created y as 2d but your assignment uses a single index. There are cases where that is valid, but I do not think those circumstances match.

When I scan your loop mentally it looks to me as if the only thing you are changing is alpha, so it looks to me as if you are wasting a lot of calculations. I might have overlooked something (middle of the night and all), but it looks to me as if your loop can only produce two different values, one for s_hy being more negative than alpha is positive, and the other for s_hy being less negative than alpha is positive (the case of exact equality seems unlikely in practice.)