function A = incidence(B)
%
% A = incidence(B)
%
% Determines incidence matrix A corresponding to edge matrix B
%
% B is a matrix with 2 columns giving the edges
% the ith row of B says which two nodes are connected by edge i
%
% See also CEDGE, NETW
nedge = size(B,1);
nvert = max(max(B));
A = zeros(nedge,nvert);
for i=1:nedge,
A(i,B(i,1)) = 1;
A(i,B(i,2)) = -1;
end