clear 
close all
figure

p=[0:.001:1];
for i=2:length(p)-1,
    H(i)=-p(i)*log2(p(i))-(1-p(i))*log2(1-p(i));
end
H(1)=0;
H(length(p))=0;
N=8;
cost=2;
HH=cost .*ones(1,length(p)) +H + p .* log2(N-1);

plot(p,HH,'-r','linewidth',1.2);
axis([0 1.1 0 7])
xlabel('P(e)')
ylabel('H(X)    [bit/simbolo]')
grid