Can this for loop be vectorized?

Question

0 个投票

The for loop below runs over the third dimension (page) to fill the alpha array. Is it possible to vectorize this for loop?

alpha_i_h_t = NaN(N_i,N_t,N_draws); 
for i = 1:N_draws
    alpha_i_h_t(:,:,i) = e_i_h(:,i) + e_h * t; 
end

2 个评论
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Torsten 2022-2-28

e_i_h(:,i) is a column vector. For e_i_h(:,i) + e_h * t to be defined, e_h * t must be a column vector or a scalar.

So how do you want to write a column vector into a matrix array alpha_i_h_t(:,:,i) ?

Bruno Luong 2022-2-28

No Torsen because MATLAB auto-expansion.

Answer 1

Bruno Luong 2022-2-28

编辑：Bruno Luong 2022-2-28

0 个投票

e_i_h_reshape = reshape(e_i_h,N_i,1,N_draws);
alpha_i_h_t = e_i_h_reshape + e_h * t; 

Torsten 2022-2-28

And why do you need a three-dimensional array for a two-dimensional content ?

Or do I get something wrong ?

Bruno Luong 2022-3-1

编辑：Bruno Luong 2022-3-1

The result is 3D, each page contains a matrix sum of column by row vector.