# rec_loop

A recursive loop function. Returns all permutations of vectors of length loop_depth containing numbers from 1 to N. E.g., loop_depth = 1 and N = 3 gives [1; 2; 3]; loop_depth = 3, N = 2 gives

1 1 1 1 1 2 1 2 1 1 2 2 2 1 1 2 1 2 2 2 1 2 2 2

The function is useful when you need to nest loops, but don't know how deep the nesting will be.

function loop_matrix = rec_loop(varargin) % loop_matrix = rec_loop(loop_depth, N) % % Thomas Gladwin, 2007. loop_depth = varargin{1}; if length(varargin) > 2, current_level = varargin{2}; N = varargin{3}; else, current_level = 1; N = varargin{2}; end; if current_level == loop_depth, loop_matrix = (1:N)'; else, loop_matrix = []; to_the_right = rec_loop(loop_depth, current_level + 1, N); for n = 1:N, [nR, nC] = size(to_the_right); loop_matrix = [loop_matrix; ones(nR, 1) * n to_the_right]; end; end;