bst_bsxfun.m

function C = bst_bsxfun(fun, A, B)
% BST_BSXFUN:  Compatible version of bsxfun function.
% 
% DESCRIPTION:
%     Matlab function bsxfun() is a useful, fast, and memory efficient 
%     way to apply element-by-element operations on huge matrices. 
%     The problem is that this function only exists in Matlab versions >= 7.4
%     This function check Matlab version, and use bsxfun if possible, if not
%     it finds another way to perform the same operation.

% @=============================================================================
% This function is part of the Brainstorm software:
% https://neuroimage.usc.edu/brainstorm
% 
% Copyright (c) University of Southern California & McGill University
% This software is distributed under the terms of the GNU General Public License
% as published by the Free Software Foundation. Further details on the GPLv3
% license can be found at http://www.gnu.org/copyleft/gpl.html.
% 
% FOR RESEARCH PURPOSES ONLY. THE SOFTWARE IS PROVIDED "AS IS," AND THE
% UNIVERSITY OF SOUTHERN CALIFORNIA AND ITS COLLABORATORS DO NOT MAKE ANY
% WARRANTY, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO WARRANTIES OF
% MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, NOR DO THEY ASSUME ANY
% LIABILITY OR RESPONSIBILITY FOR THE USE OF THIS SOFTWARE.
%
% For more information type "brainstorm license" at command prompt.
% =============================================================================@
%
% Authors: Francois Tadel, 2010

% Old Matlab version: do it old school
if ~exist('bsxfun', 'builtin')
    sA = [size(A,1), size(A,2), size(A,3)];
    sB = [size(B,1), size(B,2), size(B,3)];
    % If arguments were not provided in the correct order
    if all(sA == [1 1 1]) || all(sB == [1 1 1])
        C = fun(A, B);
    elseif all(sA == sB)
        C = fun(A, B);
    % Dim 1
    elseif (sB(1) == 1) && (sA(2) == sB(2)) && (sA(3) == sB(3))
        C = fun(A, repmat(B, [sA(1), 1, 1]));
    elseif (sA(1) == 1) && (sA(2) == sB(2)) && (sA(3) == sB(3))
        C = fun(repmat(A, [sB(1), 1, 1]), B);
    % Dim 2
    elseif (sA(1) == sB(1)) && (sB(2) == 1) && (sA(3) == sB(3))
        C = fun(A, repmat(B, [1, sA(2), 1]));
    elseif (sA(1) == sB(1)) && (sA(2) == 1) && (sA(3) == sB(3))
        C = fun(repmat(A, [1, sB(2), 1]), B);
    % Dim 3
    elseif (sA(1) == sB(1)) && (sA(2) == sB(2)) && (sB(3) == 1)
        C = fun(A, repmat(B, [1, 1, sA(3)]));
    elseif (sA(1) == sB(1)) && (sA(2) == sB(2)) && (sA(3) == 1)
        C = fun(repmat(A, [1, 1, sB(3)]), B);
    else
        error('A and B must have enough common dimensions.');
    end
% New Matlab version: use bsxfun
else
   C = bsxfun(fun, A, B);
end