%% Graphs of a hyperbolic cylinder

%% 
% Here are two ways to graph the hyperbolic cylinder 
% 
% $$x^2\,\mbox{--}\,y^2=1$$
% 
% in three dimensional space.  Because the cylinder has two pieces, 
% I need two graphs, one for each piece, displayed together.  

%% The grid 
% I start by creating the grid of points for plotting.

u=linspace(-2,2,50); v=linspace(-2,2,50);
[U,V]=meshgrid(u,v);



%%  Using mesh

mesh(cosh(U),sinh(U),V), hold on
mesh(-cosh(U),sinh(U),V), hold off

%%  Using surf

surf(cosh(U),sinh(U),V), hold on
surf(-cosh(U),sinh(U),V), hold off