Please help with plotting and for loops!

Hi,

I'm new to Matlab so, I'm trying my best! Thank you in advance for the help.

This is my code:

frequency0 = 10e9;

lambda0 = 3e8 / frequency0;

l = 0.5 * lambda0;

l = l * 39.3701;

n = 10;

delta = l/n;

Z1 = 50;

Z2 = 100;

for x = [0:delta:l]

Z0 = Z1 + (Z2 - Z1)*(x/l);

Zin_linear = Z0 * (((Z2 * cos(B* x)) + (j * Z0 * sin(B * x))) / ((Z0 * cos(B*x)) + (j * Z2 * sin(B*x))));

Z2 = Zin_linear;

endfor

plot(x,Z0);

What I'm trying to do, is for each number in x, I want to calculate the Z0 and the Zin_linear. Then I want to take Z2 and replace it with Zin_linear and then calculate a new Z0 and I want to do this until we reach l. However, when I plot this, I get one point on the graph. What am I doing wrong?

Answer 1

[Mathieu NOE]

hello

this is the typical situation when you forget to index the variable used to do the plot after the for loop

just missing the real B value (not provided) , but the code seems to work now

all the best,

frequency0 = 10e9;              
lambda0 = 3e8 / frequency0;     
l = 0.5 * lambda0;          
l = l * 39.3701;                
n = 10;                      
delta = l/n;               
Z1 = 50;                       
Z2 = 100;     
x_list = (0:delta:l);

B = 1; % put the right value here
Z0_plot = zeros(size(x_list)); % preallocation (always better)

for ck = 1:numel(x_list)
    
    x = x_list(ck);
    Z0 = Z1 + (Z2 - Z1)*(x/l);
    Zin_linear = Z0 * (((Z2 * cos(B* x)) + (1i * Z0 * sin(B * x))) / ((Z0 * cos(B*x)) + (1i * Z2 * sin(B*x))));  
    Z2 = Zin_linear;
    % for storage and plot
    Z0_plot(ck) = Z0;
end
plot(x_list,Z0_plot);

[Emily Hackett]

Thank you so much!

[Mathieu NOE]

you're welcome