可以在GNU Octave中将向量用作3D数组索引吗？

Question

Would you please tell me, whether it is possible to use a vector as a 3D array index in GNU Octave? Ideally I would like to use vector v as an index of 3D arrays d and g , ie refer to a specific array element as d(v) and g(v) , instead of using a cumbersome expression d(v(1),v(2),v(3)) . There must be a more elegant way. Please see an example below:

% specify coordinate shift to ensure positive indices
cs = [ni nj nk]

% loop over source cell coordinates
for i1 = 1:ni
  for j1 = 1:nj
    for k1 = 1:nk

    % specify source cell coordinates
    r1 = [i1 j1 k1];

    % loop over test cell coordinates
    for i2 = 1:ni
      for j2 = 1:nj
        for k2 = 1:nk

          % specify test cell coordinates
          r2 = [i2 j2 k2];

          % calculate index vector
          v = r1-r2+cs;

          % calculate Euclidean distance between source and test cell centres
          d(v(1), v(2), v(3)) = norm(r1-r2);
          g(v(1), v(2), v(3)) = exp(-img*k*d(v(1), v(2), v(3))) / 4.0 / pi / d(v(1), v(2), v(3));

        endfor
      endfor
    endfor

    endfor
  endfor
endfor

Answer 1

I don't think it is possible. You could write a intermediary function to make sub2ind achieve it though.

function ind = vec2ind(sz, vec)
    ind = sub2ind(sz, vec(1), vec(2), vec(3)); %//although even better to go vec(:,1) etc...
end

and now you can replace d(v(1), v(2), v(3)) with d(vec2ind(v)) but is that really any better? Probably best to just accept Octave's syntax on this one.