x=-3:0.001:3;ebi=0.3;
N=4;
if N==2
    CN=2*x.^2-1;
elseif N==3
    CN=4*x.^3-3*x;
elseif N==4
    CN=8*x.^4-8*x.^2+1;
else
CN=16*x.^5-20*x.^3+5*x;
end
subplot(221)
plot(x,CN);axis([-1.1,1.1,-5,5])
subplot(222)
plot(x,1./(ebi.^2*CN.^2+1))