Alternate form of eval function

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How can I write these two syntaxes in alternate from?
eval(['I',num2str(i),num2str(j),num2str(k),'=','getsiganl(filename1)',';']);
eval(['II',num2str(i),num2str(j),num2str(k),'=','smooth(sum(I',num2str(i),num2str(j),num2str(k),',2)',');']);
  1 Comment
Stephen23
Stephen23 on 18 Mar 2021
Edited: Stephen23 on 18 Mar 2021
Rather than trying to use an "Alternate form of eval function", you should just write your code using much simpler and much more efficient indexing. Is there a particular reason why you cannot use indexing?

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Accepted Answer

Bjorn Gustavsson
Bjorn Gustavsson on 18 Mar 2021
You'll have to learn good programming-habits and utilise the vectorized capabilities of matlab. This looks like a case where you might get away with multi-dimensional arrays - but that would require all your signals to have the same length. The safer option is to store all signals in a cell-array - there everything goes. Perhaps something like this:
I_all{i,j,k} = getsiganl(filename1);
I_all_smooth{i,j,k} = smooth(sum(I_all{i,j,k},2));
I would also suggest changing the indices i, j and k to i1, i2 and i3 - this makes me more comfortable when it comes to which order they should go in indexing and also leaves i and j for the imaginary constant.
HTH

More Answers (1)

Matt J
Matt J on 18 Mar 2021
Why not simply
I(i,j,k)=getsiganl(filename1);
II(i,j,k)=smooth(sum(I(i,j,k),2))
Be mindful though that if i,j,k are scalar coordinates, neither the original eval form nor the above make sense.
  2 Comments
Bjorn Gustavsson
Bjorn Gustavsson on 18 Mar 2021
If getsiganl returns a 2-D matrix it kind of makes sense, note that the eval-version would generate variables with names like I123 for i = 1, j = 2 and k = 3 and then the completely inuntangleable _I1234 for all of [i, j, k] = [12, 3 4], [1 23 4] or [1 2 34]...
Wiqas Ahmad
Wiqas Ahmad on 18 Mar 2021
@Matt J I think I have checked this in prior but haven't worked. Anyway I got the right answer. Thank you

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