function separation = getdistance(srcpos, detpos)
%  separation=getdistance(srcpos,detpos)
%
%  compute the source/detector separation from the positions
%
%    author: Qianqian Fang (q.fang <at> neu.edu)
%
%    input:
%        srcpos:array for the source positions (x,y,z)
%        detpos:array for the detector positions (x,y,z)
%
%    output:
%        separation:  the distance matrix between all combinations
%              of sources and detectors. separation has the number
%              of source rows, and number of detector of columns.
%
%    this file is part of Monte Carlo eXtreme (MCX)
%    License: GPLv3, see http://mcx.sf.net for details

srcnum = length(srcpos(:, 1));
detnum = length(detpos(:, 1));
for s = 1:srcnum
    for r = 1:detnum
        separation(r, s) = norm(srcpos(s, :) - detpos(r, :), 'fro');
    end
end