rot90 in 3D

This function extends the rot90 command to 3D.

Description

This function extends the rot90 command to 3D. So you can rotate a 3D matrix by 90degrees about the x-axis, y-axis, or z-axis. It is kind of hard to visualize in your head but I am pretty sure it works correctly. There is a test matrix included in the comments for the file.

• MATLAB release: MATLAB 7.9 (2009b)

[Jan Simon]

Help text exist, but not at the usual position. No H1-line, no check of inputs. The 3rd argument of ROT90 is optional, so a user might expect this for ROT90_3D also. The calculations are valid, but not efficient due to using loops. E.g. for M=ROT90_3D(X,1,1) this is faster: A=PERMUTE(X,[1,3,2]); M=A(:,size(X,3),:);
Further acceleration: Use same array name for input and output (see: Loren's blog "In-place Operations on Data").

[Jan Simon]

Sorry - I forgot some indices:
Y = ROT90_3D(X,1,1) equals:
  M = PERMUTE(X, [1,3,2]); Y = M(:, size(X,3):-1:1, :);
Other equivalents:
ROT90_3D(X, 1, 2):
  Y = X(:, size(X, 2):-1:1, size(X, 3):-1:1);
ROT90_3D(X, 1, 3):
  Y = PERMUTE(X(:, size(X,2):-1:1, :), [1,3,2]);

For the other dimensions, this formulas are cyclical shifted. For e.g. [100 x 100 x 100] arrays this takes about 2% of the time of ROT90_3D, so I'd suggest to update the submission.

[Matt Fetterman]

Hi Jan, Thanks for comments. I did update it. It is hard to write it using the permute command but hopefully got it right !

[Jan Simon]

Some indices are confused: Dim=2 and 3, NumRot=1 and 3. I've used your correct working first submission for checking the results. I'll try to contact you by email.