how to block diagonalize a 3D matrix

how to blkdiag a 3D matrix. The blkdiag operation is done to 2D slice along dim 3

Answer 1

[Teja Muppirala]

R = rand(4,2,3);

M = mat2cell(R,4,2,ones(1,size(R,3)));
M = blkdiag(M{:})

[Timothy]

Hmm. Make that third dimension a lot bigger.

R = rand(4,2,65341); tic M = mat2cell(R, 4,2,ones(1, size(R,3))); toc

Elapsed time is 6.065165 seconds.

I was hoping to use blkdiag to perform a [3x2] * [2 x 1] calculation a whole bunch of times, P = 65341 times. For looping through takes 2.5s. Setting up the block diagonal in this way is much slower. Is there a faster way?