Use of Circshift command : possible bug.

Hi, I am using circshift to periodically shift a 2d array. According to MATLAB documentation https://uk.mathworks.com/help/matlab/ref/circshift.html

circshift(A,[degree,dim])

shifts A by degree along dim. This works when dim=1 : I get expected result of circshift(A,[degree,1]) But for dim=2 I need to switch i.e. I have to use circshift(A,[2,degree]) to get desired result. I am using MATLAB 2016a. Please have a look.

Answer 1

[John D'Errico]

Funny, that is NOT how the documentation describes it. Here is the pertinent section:

B = circshift(A,[1 -1]) % circularly shifts first dimension values
                        % down by 1 and second dimension left by 1.

If the second argument is a TWO element vector, then the one of the elemnts is NOT the dimension. The first element tells how far to shift in dimension 1. The second element tells how far to shift in dimension 2.

If you wish to specify a circular shift dimension dim by extent k, then use THREE arguments.

 circshift(A,k,dim)

So there is a bug, but it is in your reading of the help for circshift. The help itself accurately describes what the code does.

[Pragya Srivastava]

Okay. Thanks for clarification. I was misreading [1 2] to be 1,2.