Check the flipped of 3D Array matrix

Hello everyone,

I'm construct the multi dimensions 3D [X,Y,Z double] matrix.

Suppose I have

A = zeros(3,6,3);
A(:,:,1) = [1 2 3 3 2 1
            2 2 3 3 2 2
            3 3 4 4 3 3];

A(:,:,2) = [1 1 3 3 1 1
            0 0 3 3 0 0
            5 5 6 6 5 5];

A(:,:,3) = [0 0 3 3 0 0
            1 1 3 3 1 1
            5 5 1 1 5 5];

As we can see, along through Z-axis ( the center in column 1 to column 3 can be flipped as column 4 to 6

Do we have any way to check and return as logical value (0,1) to show this multidimension arrays are fliped or not.

Thanks in advances.

[Benjamin Thompson]

Can you define what "flipped" means? You can review the contents of your matrix in MATLAB after creating it.

[Trang Hu Jia]

Dear @Benjamin Thompson

Thek you very much for replying this topic.

The "flipped" that I mean is in page 1 to 3 (in Z-axis)

Column 3 are exactly the same in column 4, Column 2 are exactly the same in column 5 and so on.

This matrix I can directly check it easily.

However, suppose I have larger matrix in X rows and Y columns, do we have any way to check it by logical ?

Thanks in advances.

Answer 1

[Jan]

Do you mean:

isequal(A, flip(A, 2))

If A is huge (e.g. 1 GB), this operation is not efficient, because it duplicates the Array. If this is the bottleneck of you code, you could to the comparison in a C-mex function. This will be a little bit slower for small A (I estimate until 1000 elements), but much faster if e.g. the first element does not match already and the function can reply FALSE soon.

Do you need such a C-mex function?

[Trang Hu Jia]

Dear @Jan

Thank you for your replying.

This help me a lot.

Thank you very much.