% MR = distribute_random(M,distribution,sigma_dist) takes the nonzero values in
% M as the mean of a distribution and replaces its value with one drawn
% from the distribution.
% distribution specifies the kind of distribution,
% that is used. 0: no distribution, 1: uniform (sigma_dist*mean is the
% range), 2: gaussian (sigma_dist*mean gives the HWHH of the distribution),
% the weights are normalized, to keep the sum of the matrix constant.
% created: Jakob Heinzle 01/07