MATLAB: Sort first column of a 5×2 matrix but keep the rows intact after sorting

arrayMATLABsort

Hi, I have a 5×2 matrix and I would like to sort the first column and keep the rows together after the sorting is done. For example, I have an array given by
UP = zeros(5,2)
ai  = [13,11,15,26,20]
for i = 1:5
    UP(i,1) = ai;
    UP(i,2) = i;
end
After I sort the first column of the array, I would like to keep the second column assigned with the value of the first column. I would like an output that looks like the following
11,2
13,1
15,3
20,5
26,4

Best Answer

Use sortrows:
>> V = [13,11,15,26,20];
>> M = [V;1:numel(V)].'
M =
   13    1
   11    2
   15    3
   26    4
   20    5
>> Z = sortrows(M,1)
Z =
   11    2
   13    1
   15    3
   20    5
   26    4
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