MATLAB: Create a 3D matrix from multiple 1D vectors without FOR loop

Question

Hello everyone,

I would like to construct a three-dimensional 3x3xL matrix from a series of one-dimensional vectors.

So far I achieve this with the following code:

St = zeros(3.0, 3.0, L);
for i = 1:L
    St(:, :, i) = [Sxxi(i), Txyi(i), Txzi(i);...
    Txyi(i), Syyi(i), Tyzi(i);...
    Txzi(i), Tyzi(i), Szzi(i)];
end

Where each of the six tensor components is a vector of size 1xL. I find this code to be quite silly and unnecessarily slow.

I'm wondering if there's a way to concatenate the six components into the 3x3xL matrix without using a FOR loop? At fist glance it looks like this might be achievable with CAT() but I'm not sure how this would work.

The parameter L is arbitrary so I'm trying to develop a solution which works for any length.

Thanks in advance,

Louis Vallance

Answer 1

St=reshape(   [Sxxi;Txyi;Txzi; Txyi;Syyi;Tyzi; Txzi;Tyzi;Syyi]  , 3,3,[])