![]() ![]() No needs to generate a googleplex of permutation matrix. You're trying to solve the assignment problem, you can use the well known hungarian algorithm to solve this task in polynomial time. function I, PMat permutationFromTo (A,B) ,IA sort (A) ,IB sort (B) I (IB) IA PMat (:,I) eye (length (A)) You can use it via: A rand (10,1) B A (randperm (10)) I, PMat permutationFromTo (A,B) // All the following three lines will output the vector B. Them one by one and get the result of multiplication. Permutation matrices and store them in such variable, I can generate permute does a permutation of the dimensions of an array, not of its elements, as one may expect from its name. Resulting a tr(Y) minimum where Y is the results of multiplication of It has various features like dimension, size, circshift, and reshape. ![]() To access this command we just need to pass the order of the multi-dimensional matrix. Permutation matrices and choose that permutation matrix which Introduction to Permute Matlab ‘Permute’ command in Permute Matlab is used to rearrange the elements within a multidimensional array. What I need to do is to multiply a matrix i.e Z with all possible Res = reshape(rep(:,perms(1:n).'),n,n,f) % indexing and reshaping Rep = repelem(eye(n),1,1,f) % repeat n! time the diagonal matrix ![]() This may not be the approach actually used by Matlab, though.Using repelem, perms and reshape: n = 3 % matrix sizeį = factorial(n) % number of permutation Putting these three facts together shows that it is possible to do it without a significant amount of extra memory. Transposition can be done inline, requiring only a fixed amount of extra memory, independent of array size, or growing very slowly with array size. Permute(., ) %// interchange dims 3 and 4: we have dims Įach of these elementary operations (interchanging two dimensions) is essentially a transpose along a given plane of the multidimensional array, performed repeatedly along all other dimensions. Permute(., ) %// interchange dims 2 and 4: we have dims For example, permute(x, ) is equivalent to this sequence of elementary permute operations (the sequence is not unique): permute(., ) %// interchange dims 1 and 4: we have dims T Theme Copy A -1 -1 1 1 -1 0 -3 0 1 1 0 0 B perms (A) Sign in to comment. I use below codes, it gives irrevalent result. But I couldn't figure out how to make on MATLAB. So I need to find permutation matrix for A (sc). Permuting of dimensions can always be done as a sequence of elementary permute operations, where" elementary" means interchanging only two dimensions. Some step of works wanted to find permuation matrix. This is only a guess, as I don't really know what permute does under the hood. While this is not exactly the best way to profile memory usage (better use a proper memory profiler, something like Intel Inspector XE), it does show to some degree that permute is indeed not working in-place. ipermute Inverse permute array dimensions. ind2sub Multiple subscripts from linear index. You can see how at its peak the function reached twice as much memory usage as when it returned. 2.3 M-le functions sub2ind Linear index from multiple subscripts. I also repeated the test under perfmon.exe which showed the same pattern: I then ran the function simply as: %clear aĪnd watched the memory usage It went from 1.8 gigs in use, and rose to 5.2 then quickly down to 3.6 gigs. r1 randperm (8,4) r1 1×4 6 4 7 3 Generate another random permutation of four unique integers. I only have 8 gigs of RAM on my laptop, so to avoid thrashing I modified your function as: function out = mtest() Permute a Selection of Integers Try This Example Copy Command Generate a random permutation of four unique integers (without repeating elements) selected randomly from the integers 1 to 8. I also set the "update speed" to "high" to get a finer time resolution. In Windows 10, I opened the "task manager" on the "performance" tab with the "memory" graphs in view. The permute method in fact does create a second copy of the matrix with the data permuted and returns it. Your argument is flawed because the MATLAB memory profiler is not telling you the truth!
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