MATLAB: Sortrows descend not working

descendMATLABsortrows

Hello,
I have a matrix created in Matlab and I want to sort its rows in descending order, keeping the rows unchanged. Specifically, I want to sort rows according to value in the first column in descending order; if two rows have the same values in the first column, I want to sort the rows in descending order according to the value in the second column; and so on.
My matrix's name is "up2" and I am using the code "up2=sortrows(up2,'descend');" to obtain the sorted matrix. However, as the figure below shows sorting is not working. The figure is showing the sorted matrix after I run the code. The first four columns of rows 6 and 7 have the same values, so accroding to the values in column five row 6 should be below row 7, but it is not.
Can you please help to fix the problem? Thanks!
By the way, if it is related, col4=1-col5+col10 and col10=1-col8+col1.*log(col6+col9). When I copy the values of the first four columns here, the two rows seem to have exactly the same values:
col1 col2 col3 col4
1.20000000000000 0.100000000000000 0.200000000000000 0.832227738422948
1.20000000000000 0.100000000000000 0.200000000000000 0.832227738422948

Best Answer

My best guess is that the first four values are not exactly the same but differ by an amount around the floating point precision. What does
up2(7,1:4) - up2(6,1:4)
give?
(If you could upload the variable here, in a MAT file, that would be helpful for investigating.)
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