%%%%%%%%%%%%%%%%%%%%% Convert Euclidean to Hyperbolic %%%%%%%%%%%%%%%%%%%%%
%
% EUCTOHYP
% Usage: h = EUCTOHYP(r)
% Inputs:  r a real number satifying -1 < r < 1
%
% Outputs: the real rumber h which is the hyperbolic distance for zero 
%          multiplied the sign of h so that h and r have the same sign 

function h = euctohyp(r)             
         h = log((1+r)/(1-r));