an implementation of combvec that anyone can use, ie for octave or missing nnet

mtcombvec.m

function c = mtcombvec(varargin)
% my own implementation of combvec for use in octave or without matlab nnet library
% 
% takes args of column-vectors, produces all combinations thereof
%

% copyright (c) 2018 Michael Tesch, tesch1@gmail.com
% released under the Apache 2.0 Open Source license.

if length(varargin)==0
    c = [];
    return
end

c = varargin{1};

for i=2:length(varargin)
    % make sure varargin{i} isn't more than 2d matrix
    if length(size(varargin{i}))>2
        error(sprintf('parameters must be 2d matrices (check arg %d)', i));
    end
    c = mtextend(c, varargin{i});
end

function cc = mtextend(old, new)
mm = size(old,2);
nn = size(new,2);
cc = repmat(old, 1, nn);
cc = [cc ; repmat(new, 1, mm)];