function N_test
V = 1;
P = 30e5;
open ../Plotting/Ph_diagram.fig
h=[];Ptmp=[];
for T = 273:-1:260
  N = N_given_TVP([T; V; P],'v')
  h = [h; h_given_TVN([T; V; N])];
  Atmp = co2_sw([T; V; N]);
  Ptmp = [Ptmp; -Atmp.g(2)];
end
P-Ptmp
hold on
semilogy(h, Ptmp)
hold off
