function [R C] = p3p_RC( N, u, X, K )
%P3P_RC  P3P problem - absolute camera pose and orientation
%   [R C] = p3p_RC( N, u, X )
%     
%   Input:
%     N .. 1x3, distances (eta) along rays, single solution, obtained from
%           p3p_distances. If [N1 N2 N3] = p3p_distances( ... ), then for 
%           particular i the distances are 
%                 N = [ N1(i) N2(i) N3(i) ]
%     u .. 2x3, corresponding three image points (column vectors)
%
%     X .. 3x3, corresponding three 3D points (column vectors)
%
%     K .. 3x3 calibration matrix
%       
%   Output:
%     R .. matrix of rotation (3x3)
%     C .. camera centre
