I have a big matrix A which is 1GB of double values, when I reshape it to different dimensions, it's incredible fast.
A=rand(128,1024,1024);
tic;B=reshape(A,1024,128,1024);toc
Elapsed time is 0.000011 seconds.
How can it be that fast? Another observation, MATLAB uses less memory than it should after running that code and storing two matrices of 1GB each: Memory used by MATLAB: 1878 MB (1.969e+09 bytes)