create_linear_index_list.m

The Finite Difference Time Domain Method for Electromagnetics With MATLAB Simulations Atef Elshe

% a function that generates a list of linear indices 
function [fi] = create_linear_index_list(array_3d,i_list,j_list,k_list)

i_size = size(i_list,2);
j_size = size(j_list,2);
k_size = size(k_list,2);
number_of_indices = i_size * j_size * k_size;
I = zeros(number_of_indices,1);
J = zeros(number_of_indices,1);
K = zeros(number_of_indices,1);
ind = 1; 
for mk = k_list(1):k_list(k_size)
    for mj = j_list(1):j_list(j_size)
        for mi = i_list(1):i_list(i_size)
            I(ind) = mi;
            J(ind) = mj;
            K(ind) = mk;
            ind = ind + 1;
        end
    end
end
fi = sub2ind(size(array_3d), I, J, K);