%function y = y_ex(t, y0, C, B)
function y = y_ex(t)
  y0 = .1;
  B = 10;
  C = 2;
  K = y0/(1 - y0/B);
  y = K*exp(C*t)./(1 + K/B*exp(C*t));
  y = y';
end
