% exercise 8.something
set(0,                           ...
   'defaultaxesfontsize', 20,   ...
   'defaultaxeslinewidth', 1.2, ...
   'defaultlinelinewidth', 2.0, ...
   'defaultpatchlinewidth', 0.7); 

c = [-10:.01:10];
kplist = [100,10 1];

for j = 1:length(kplist)
    kap = kplist(j)

f=(sqrt(c.^2+1)-c)./(sqrt(c.^2+1)+sqrt(c.^2+1 +kap));
plot(f,c,[0 1],[0 0],'--','linewidth',2)
hold on
end
xlabel('P','fontsize',20)
ylabel('c','fontsize',20)
hold off
