function A = normu(u);

% NORMU Normalizes image points to be used for LS estimation.
%       A = NORMU(u) finds normalization matrix A so that mean(A*u)=0 and mean(||A*u||)=sqrt(2).
%       (see Hartley: In Defence of 8-point Algorithm, ICCV`95).
%       Parameters:
%         u ... Size (2,N) or (3,N). Points to normalize.
%         A ... Size (3,3). Normalization matrix.

if size(u,1)==3, u = p2e(u); end

m = mean(u')'; % <=> mean (u,2)
u = u - m*ones(1,size(u,2));
distu = sqrt(sum(u.*u));
r = mean(distu)/sqrt(2);
A  = diag([1/r 1/r 1]);
A(1:2,3) = -m/r;

return