plotting for loop answers with changing variables

Hello

I am running into an issue with some code I am writing for a class, I have defined the mathematical aspect of the code, which gives me the answer I need for on simulation, but how would I go about plotting the same code but variables changing in step intervals? I am new to indexing and I believe that may be the answer to my question but I am unsure how to execute it in this example.

I want to re run the code for KC to start from 2 to 20 in 2 step intervals to compare results and overlay them for my power plot, and run another simulation where I keep KC constant but change one of my other constants to an interval in the same fashion and overlay results etc, the problem is I do not know if I need to have multiple for loops or just an indexing line?

%% Variables
KC = 2
pi = acos(-1);
Um = 1.6;
T = 1.8 %(KC*D)/Um;
D = 0.16;
L = 1;
m = 50;
rho = 1024;
K = 200;
c = 100;
CA = 1;
CD = 1.8;
omega = 2*pi/T;
md = 1;
Ap = D*L;
dt = T/40;
ndt = T/dt*5;
X(1:ndt+1) = 0;
V(1:ndt+1) = 0;
%% Governing equations

time(1:ndt+1) = (0:ndt)*dt;
P(1:ndt+1)= 0;
Pavg=0;
Kc=(Um*T)/D;

for n=1:ndt,
    %for KC = 2:2:20,
    % Calculation of kx1 and kv1
    ta= time(n);
    aw= omega*Um*cos(omega*ta)-(2*Um*omega*cos(omega*ta))/3;
    Vw= Um*sin(omega*ta)- (Um/3)*sin(2*omega*ta);
    Va= V(n);
    Xa= X(n);
    t1= CA*md*aw;
    t2= 0.5*rho*CD*Ap*abs(Vw-Va)*(Vw-Va);
    t3= -K*Xa-c*Va;
    kx1= V(n);
    kv1= (t1+t2+t3)/(m+CA*md);
    
    %% Calculation of kx2 and kv2
    ta= time(n)+dt/2;
    aw= omega*Um*cos(omega*ta)-(2*Um*omega*cos(omega*ta))/3;
    Vw= Um*sin(omega*ta)- (Um/3)*sin(2*omega*ta)
    Va= V(n)+0.5*dt*kv1;
    Xa= X(n)+0.5*dt*kx1;
    t1= CA*md*aw;
    t2= 0.5*rho*CD*Ap*abs(Vw-Va)*(Vw-Va);
    t3= -K*Xa-c*Va;
    kx2= V(n)+0.5*dt*kv1;
    kv2= (t1+t2+t3)/(m+CA*md);
    
    %% Calculation of kx3 and kv3
    ta= time(n)+dt/2;
    aw= omega*Um*cos(omega*ta)-(2*Um*omega*cos(omega*ta))/3;
    Vw= Um*sin(omega*ta)-(Um/3)*sin(2*omega*ta);
    Va= V(n)+0.5*dt*kv2;
    Xa= X(n)+0.5*dt*kx2;
    t1= CA*md*aw;
    t2= 0.5*rho*CD*Ap*abs(Vw-Va)*(Vw-Va);
    t3= -K*Xa-c*Va;
    kx3= V(n)+0.5*dt*kv2;
    kv3= (t1+t2+t3)/(m+CA*md);
    
    %% Calculation of kx4 and kv4
    ta= time(n)+dt;
    aw= omega*Um*cos(omega*ta)-(2*Um*omega*cos(omega*ta))/3; % acceleration of the fluid
    Vw= Um*sin(omega*ta)- (Um/3)*sin(2*omega*ta); % velocity of the fluid
    Va= V(n)+0.5*dt*kv3;
    Xa= X(n)+0.5*dt*kx3;
    t1= CA*md*aw;
    t2= 0.5*rho*CD*Ap*abs(Vw-Va)*(Vw-Va);
    t3= -K*Xa-c*Va;
    kx4= V(n)+dt*kv3;
    kv4= (t1+t2+t3)/(m+CA*md);
    
    %% Step Equations
    X(n+1)= X(n)+(dt/6)*(kx1+2*kx2+2*kx3+kx4);
    V(n+1)= V(n)+(dt/6)*(kv1+2*kv2+2*kv3+kv4);
    P(n+1)= c*(V(n)^2);
    Pavg= P(n)+(1/ndt)*P(n);
end %end

%% Plot of cylinder displacement, velocity and power output
% X Displacement plot
figure (1);
plot(time(1:ndt),X(1:ndt),'-g');
xlabel('time (s)');
ylabel('X (m)');
title('X displacment');
legend ('RK method');

% V Velocity plot
figure (2);
plot(time(1:ndt),V(1:ndt),'-b');
xlabel('time (s)');
ylabel('V (m/s)');
title('V Velocity');
legend ('RK method');

% P Power plot
figure (3);
plot (time(1:ndt),P(1:ndt),'-b');
xlabel('time (s)');
ylabel('P (W)');
title('P Power');
legend ('R-K method');

hold;

After writing the code I am now confused on what to do since the second for loop I have implemented doesnt seeem to do anything and the results are the same so I am confused as to why or how to actually get it to do what I want it to?

note: I took out the second loop and replaced the variable KC with a constant to get one answer.

[DGM]

You're using both KC and Kc as parameters, but neither of them are used for anything. If you want to vary Kc, you'll have to recalculate things that depend on it.

For plotting, you can either store the results in an array and then plot them, or you can write a function to handle plotting tasks and then call it (though that may be more cumbersome to get legends, etc correct).

[Muamin Sulaiman]

I renamed Kc to KC, and i am receiving different results everytime I change the variable in line 2 now.

Could I maybe vector the KC value to acheive what I want? or maybe start a for loop at line 2 and end it at the end of the original for loop?

Thanks for bringing my attention to the parameters being named differently, that helped me :)

I will have to research storing array results and plotting them, I dont believe I have done that before.

[DGM]

Your results are already vectors, so if they're all the same length each time, just concatenate them into a 2D array.

If they're not the same length, you'd have to use a cell array or take a different approach.