plotting Intensity function which consists of an exponential sum

hello,
Im trying to plot the followin function in matlab:
where k=10,d=1,A=1,0.1,0.01, epsilon is a random number between [0,1], the summation n is from 1 to 20 and theta goes from [-pi/2,pi/2]
I've written this code:
% param defenition %
L=100; N=20; d=1; k=10; Ar=1;
A=0.1;
theta=linspace(-pi/2,pi/2,200);
phase=(d+A*epsilon)*sin(theta);
epsilon=rand(0,1);
function psi = Psi(x)
psi=1;
for n=1:N
psi=psi+(exp(i*k*phase).^n);
end
end
I=([abs(psi)].^2);
fplot(I,[-pi/2,pi/2])
but when I try to run it, I get nothing printed in the figure. what did I do wrong?
Thank you very much for your time and attention.

3 个评论

Remove function declaration and corresponding end, then replace fplot with plot(I)
thank you for your reply, but it still doesn't work. perhaps you have another idea? now it looks like this:
%% Question 03 %%
% param defenition %
L=100; N=20; d=1; k=10; Ar=1;
A=0.1;
theta=linspace(-pi/2,pi/2,200);
epsilon=rand(0,1);
phase=(d+A*epsilon)*sin(theta);
psi=1;
for n=1:N
psi=psi+(exp(i*k*phase).^n);
end
I=((abs(psi)).^2);
plot(I)
rand(0,1) returns empty vector. So instead provide rand(1,1)

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回答(1 个)

Try this:
L=100; N=20; d=1; k=10; Ar=1;
A=0.1;
theta=linspace(-pi/2,pi/2,200);
epsilon=rand;
phase=(d+A*epsilon)*sin(theta);
psi=1;
for n=1:N
psi=psi+(exp(1i*k*phase).^n);
end
I=((abs(psi)).^2);
plot(I)

2 个评论

it worked! thank you so much! I had no idea I need to use rand instead of rand(0,1). how can you keep track between all the changes in different versions? thanks once again!
I pay attention to details :) you are welcome.

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