This function takes as an input a square matrix and returns two outputs. The first is a vector containing the matrix values starting in the (1,1) entry and progressing along the anti-diagonal elements. A second output gives the sum of the elements along the anti-diagonals.
a = [1 2 3; 4 5 6; 7 8 9];
[b,c] = diagtrav(a);
b = [1 2 4 3 5 7 6 8 9];
c = [1 6 15 14 9];
Loïc (2021). Anti-diagonal matrix traversal (https://www.mathworks.com/matlabcentral/fileexchange/27688-anti-diagonal-matrix-traversal), MATLAB Central File Exchange. Retrieved .
Thank you for your suggestion, this is my first submission. I have updated the file.
As it is, you have some deficiencies. There is no H1 line. The help is non-standard in its location. There is no input checking: if the function is for square matrices then you should check to see if the input is square. Your algorithm works well, except you cripple the speed by not pre-allocating your return arrays before the loops. Look at the difference:
>> M = round(rand(400)*300);
>> tic,[P,Q]=diagtrav(M);toc % No pre-allocation
Elapsed time is 134.937511 seconds.
>> tic,[P,Q]=diagtrav(M);toc % With pre-allocation
Elapsed time is 0.014006 seconds.
You should pre-allocate the return arrays!
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