p=2^-5

p = 0.25;
for i=1:100
  deltap = (.5*p^-.2+.5*p^-.5-2)/(.1*p^-1.2 + .25*p^-1.5);
  p = p + deltap;
  if abs(deltap) < 1.e-8, break, end
end 
disp(p);

q = (0.5:0.1:2.2)';
P = zeros(length(q),1);
for j=1:length(q)
    p = 0.25;
    for i=1:100
        deltap = (.5*p^-.2+.5*p^-.5-q(j))/(.1*p^-1.2 + .25*p^-1.5);
        p = p + deltap;
        if abs(deltap) < 1.e-8, break, end
    end 
    P(j) = p;
end;

disp([q P]);

plot(q,P);
ylabel('Precio');
xlabel('Cantidad');

pi = interp1(q,P,1.456)