Alternate form of eval function

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Wiqas Ahmad
Wiqas Ahmad 2021-3-18
评论： Wiqas Ahmad 2021-3-18
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)',');']);
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Stephen23
Stephen23 2021-3-18
编辑：Stephen23 2021-3-18
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?
https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

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采纳的回答

Bjorn Gustavsson
Bjorn Gustavsson 2021-3-18
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

更多回答（1 个）

Matt J
Matt J 2021-3-18
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 个评论
Bjorn Gustavsson
Bjorn Gustavsson 2021-3-18
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 2021-3-18
@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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