MATLAB: Putting random values in for loop

for loop

Hi everyone

I am writing a program in which i am using the following loop.

for t = 1:1:81; 
    vv(t) = floor(+1*120*sin(2*pi*(t-1)/40)); 
end

The vales of vv are like 0,18,37…… However, i found that my program has some instability due to jumping directly from vv = 0 to vv = 18. Therefore, my intention is to keep the inputs for the loop as it is (otherwise it gets too long to run), but to put few more input values for vv. for example I want to start with 0, 1, 5, 9, 14, 18,37,……. Hence i need to put those 4 values in between 0 and 18 to bring stability into the result. Can anyone please help me.

Thanks in advance

Hossain

Best Answer

Do what Matt suggested:

 VV = floor(+1*120*sin(2*pi*(t-1)/40));

Then add your extra values into VV:

 VV = [VV(1) 1 5 9 14 VV(2:end)];

Then run your loop

 for i=1:numel(vv) % presumably 85
      vv = VV(i);
      % your other code
 end

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You have

function [s]= sin_c(x) 
    if x ==0
        s = 1;
    else
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    end
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In MATLAB, an if is considered to be true only if all of the comparisons are true. Your code is equivalent to

function [s]= sin_c(x) 
    if all(x ==0)
        s = 1;
    else
        s = sin(x)./(x);
    end
end

The difference between these is important because you are passing in a vector of x values, and most of them are not 0.

You might be tempted to change to if any(x == 0) but that will be true for the entire vector because of the 0 at the beginning of the vector, so you would return the scalar constant 1 instead of the correct vector value.

... Time for you to start using logical indexing.

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Assuming that myfun outputs a 5-element vector, just use indexing like this:

phi = 0.5:0.2:1.5;
mat = nan(5,numel(phi));
for k = 1:numel(phi)
    mat(:,k) = myfun(3000,1,phi(k));
end

This puts each result as one column of mat, which makes plotting easier. Or you could swap the dimensions of mat to put the results as rows. Whatever works for you.

Best Answer

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