MATLAB: Extract matrix from for loop

for loop matrix

Hi,
I want to extract a 2×2 matrix from each iteration of a for loop. Normally I would use something like
for loop=1:1:10
m=[a b c d];
m2(loop)=m;
end
but this doesn't work because of the increased dimensions. Can anyone help?

Best Answer

Use cell arrays, or stack along the third dimension.
for loop=1:1:10
   m=[a b c d]; % I assume this is only a place-holder for code.

   m2{loop}=m;  % Notice the curly braces, not parenthesis.
end
Or,
for loop=1:1:10
   m=[a b c d]; % I assume this is only a place-holder for code.
   m2(:,:loop)=m;  % A 3D array.  Each page is a matrix
end
Also note, that if your final array m2 will be much larger than this you will definitely want to pre-allocate the space.
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