function ss = outer_sum(xx,yy)
%function ss = outer_sum(xx,yy)
% compute an "outer sum" x + y'
% that is analogous to the "outer product" x * y'
% in
%	xx [nx,1]
%	yy [1,ny]
% out
%	ss [nx,ny]	ss(i,j) = xx(i) + yy(j)
% Copyright 2001, Jeff Fessler, The University of Michigan

if ~nargin, help outer_sum, end

xx = xx(:);
yy = yy(:)';
nx = length(xx);
ny = length(yy);
xx = xx(:, ones(1,ny));
yy = yy(ones(1,nx),:);
% [xx, yy] = ndgrid(xx, yy);
ss = xx + yy;