Try lots of differences way simplifying my code but doesn't work well. How can I fix it?

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chia ching lin 2020-10-27

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评论： chia ching lin 2020-10-28

Need help for simplifying my matlab code. I have tried function handle, cellfun, anonymous function, arrayfun. I do not know am I using those function fully correct, but the outcome doesn't really satisfy my requirment.

lambda = 1;
k = 2*pi/lambda;
w = 2*pi*v/lambda;
z=linspace(0,10,10000);
t=linspace(0,10,10);  %time
theta=(pi)*rand(1,length(t));   %random phase
for a=1:length(t)
    u1=1./(1+exp(-2.*(10e4).*(t(a)-z./v)));   %step function
    u2=1./(1+exp(-2.*(10e4).*(t(a)-z./v-1)));
    u3=1./(1+exp(-2.*(10e4).*(t(a)-z./v-2)));
    u4=1./(1+exp(-2.*(10e4).*(t(a)-z./v-3)));
    u5=1./(1+exp(-2.*(10e4).*(t(a)-z./v-4)));
    u6=1./(1+exp(-2.*(10e4).*(t(a)-z./v-5)));
    u7=1./(1+exp(-2.*(10e4).*(t(a)-z./v-6)));
    u8=1./(1+exp(-2.*(10e4).*(t(a)-z./v-7)));
    u9=1./(1+exp(-2.*(10e4).*(t(a)-z./v-8)));
    u10=1./(1+exp(-2.*(10e4).*(t(a)-z./v-9)));
    del_u1=u1-u2;
    del_u2=u2-u3;
    del_u3=u3-u4;
    del_u4=u4-u5;
    del_u5=u5-u6;
    del_u6=u6-u7;
    del_u7=u7-u8;
    del_u8=u8-u9;
    del_u9=u9-u10;
    y1=del_u1.*cos(k.*z-w.*t(a)+theta(1));
    y2=del_u2.*cos(k.*z-w.*t(a)+theta(2));
    y3=del_u3.*cos(k.*z-w.*t(a)+theta(3));
    y4=del_u4.*cos(k.*z-w.*t(a)+theta(4));
    y5=del_u5.*cos(k.*z-w.*t(a)+theta(5));
    y6=del_u6.*cos(k.*z-w.*t(a)+theta(6));
    y7=del_u7.*cos(k.*z-w.*t(a)+theta(7));
    y8=del_u8.*cos(k.*z-w.*t(a)+theta(8));
    y9=del_u9.*cos(k.*z-w.*t(a)+theta(9));
    y10=u10.*cos(k.*z-w.*t(a)+theta(10));
    yy=y1+y2+y3+y4+y5+y6+y7+y8+y9+y10;
    figure(1)
    plot(z,yy); grid on; axis image;
    drawnow;
end

The equation is not complicated but I got hard time trying to simplify it. I'm suppose to repeat the equation 1000 times, means length(theta)=1000, u1~u1000, del_u1~del_u999, y1~y1000, yy=y1+y2+...y1000.

How can I simplify my code?

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Stephen23 2020-10-27

"How can I simplify my code?"

Do NOT use numbered variables.

Using numbered variables like that is a sign that you are doing something wrong.

MATLAB is designed for operating on entire vectors/matrices, and that is what you should do too. Splitting up your data into numbered variables forces you into either repeating code many times or using slow and inefficient methods to access your data. Do not make accessing your data so difficult!

Keep data together in vectors/matrices. When possible apply operations to the entire vectors/matrices:

https://www.mathworks.com/help/matlab/matlab_prog/vectorization.html

When required use loops and indexing. That is how you will simplify and improve your code.

chia ching lin 2020-10-28

Thanks for giving the advice. I've tried using the vector/array already, I used function handle and cellfun.The problem when I'm using them is u and y have the t (time) in it, which I want to animate, but cellfun can only output scalar. Also the theta in y is random, it need to go with y and not changing while t is changing. That is the two main point why I comes back and tried it with the most stupid way. Any other function recommend?

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Try lots of differences way simplifying my code but doesn't work well. How can I fix it?

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Try lots of differences way simplifying my code but doesn't work well. How can I fix it?

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