What type of sort does the SORT function in MATLAB perform?

Could you tell me the algorithm and/or the running time of the SORT function?

I need to know which sorting algorithm is used by MATLAB when the SORT function is executed.

Answer 1

[MathWorks Support Team]

The type of sort that is done is a Quick Sort. It is not an 'adaptive sorting' algorithm, and does not deviate much from the standard Quick Sort algorithm. Quick Sort has been found to be one of the fastest algorithms for sorting; it is an O(n log n) operation. We do not have specific time information, since it depends on both the system and the numerical data used in the sort.

[sidharth]

MATLAB uses 2 partition quicksort or 3 partition quicksort for sorting operation ??

[Royi Avital]

Is it a stable implementation of QuickSort?

Answer 2

[Alex]

Hi MathWorks Support Team.

I wonder whether you can tell me whether the quicksort algorithm you have implemented keeps the within group ordering. Here is a link to my original question on Stack Overflow:

https://stackoverflow.com/questions/32322908/does-sortrows-always-preserve-the-original-ordering-within-sorting-groups/32324683#32324683

[Walter Roberson]

Yes, the sort is stable; see http://www.mathworks.com/company/newsletters/articles/an-adventure-of-sortsbehind-the-scenes-of-a-matlab-upgrade.html

[Eli4ph]

Also, one can check by

edit sort

There is a sentence in comment saying

%   When more than one element has the same value, the order of the
%   elements is preserved in the sorted result and the indices 
%   relating to equal elements will be ascending.