Matlab doesn't save the new variable to the Workspace?

Hi, I have written a code that needs the number of rebounds of moving particles in a 2D box, now I needed to count the number of rebounds when the grid becomes bigger. This all works but my C isn't saved to the workspace, I need this to apply Curve Fitting. According to the Workspace C are all zeros.

This is my code:

N = 1000;
T = 1000;
L = 1:1:150;
l = 1:1:150;
C = zeros(size(L));
velocityx = randi([-1,1],N,1);
velocityy = randi([-1,1],N,1);
dt = 1;
Velocity = Inlet(N, velocityx, velocityy);
function Velocity = Inlet(N, velocityx, velocityy);
Velocity = [velocityx, velocityy];
N = 1000;
T = 1000;
L = 1:1:150;
l = 1:1:150;
C = zeros(size(L));
velocityx = randi([-1,1],N,1);
velocityy = randi([-1,1],N,1);
dt = 1;
for L = 1:1:150
    x = randi([1,L],N,1);
    y = randi([1,L],N,1);
    for t = 1:1:T
        for i=1:1:N
            x(i) = x(i)+velocityx(i)*dt;
            y(i) = y(i)+velocityy(i)*dt;
        end
        %Collisions
        for i=1:1:N
            %Collisions with the Y-axis bounds
            if  0 == x(i) %Collision with chamber wall
                C(L) = C(L)+1;
                velocityx(i) = -velocityx(i)*dt;
                velocityy(i) = randi([-1,1]);
            end
            if (L+1) == x(i) %Collision with chamber wall
                C(L) = C(L)+1;
                velocityx(i) = -velocityx(i)*dt;
                velocityy(i) = randi([-1,1]);
            end
            % Collisions with the X-axis bounds
            if 0 == y(i) %Collision with chamber wall
                C(L) = C(L)+1;
                velocityy(i) = -velocityy(i)*dt;
                velocityx(i) = randi([-1,1]);
            end
            if (L+1) == y(i) %Collision with chamber wall
                C(L) = C(L)+1;
                velocityy(i) = -velocityy(i)*dt;
                velocityx(i) = randi([-1,1]);
            end
        end
    end
    Velocity = [velocityx, velocityy];
    idx = Velocity(:,1) == 0;
    vec = [1; -1];
    Velocity(idx,2) = vec(randi(numel(vec),nnz(idx),1));
end
plot(C);
corrcoef(C,l);
end

This is a C according to my code:

Columns 145 through 151

        8654        8623        8644        8555        8484        8422        8365

And this is what C is according to the workspace:

0	0	0	0	0	0	0	0	0	0	0	0

How can I now make sure that the C in the workspace is also the C that my function gives?

Answer 1

[Image Analyst]

Each function or script in your code has its own private workspace. So the C in your script is different than the C in your function. If you want the C in your function to be passed out and replace the zeros that it started out with you need to declare it like this:

function [Velocity, C] = Inlet(N, velocityx, velocityy);

and call it like this:

[Velocity, C] = Inlet(N, velocityx, velocityy);

[Danny Helwegen]

So i replaced the first two lines of the function too:

function [Velocity, C] = Inlet(N, velocityx, velocityy);
[Velocity, C] = Inlet(N, velocityx, velocityy);

But then i get this error:

Out of memory. The likely cause is an infinite recursion within the program.

Error in Untitled99>Inlet (line 11)
[Velocity, C] = Inlet(N, velocityx, velocityy);

[Image Analyst]

WHY are you now having the Inlet function call itself??? Why did you do that? I did not tell you to do that. I told you to change the function definition, and the way you call it in your main calling routine (your script above your function). Do what I said and it should work.

[Danny Helwegen]

Ah I see, I shouldn't put it in the function but above. My problem is solved now, he gives me now the result for C in the workspace.

Thank you