clear all
figure (2)
subplot(2,2,1)
x=-4:0.001:4;
y=1./(1+exp(log(0.25)*x));
plot(x,y)
grid on
subplot(2,2,2)
%temp=sqrt(log(0.5)/log(0.8));
x=-0.75:0.001:2;
a=log(0.5)/log(0.5/0.2);
k=log(0.5/0.2);
y=1-exp(-k.*(x-a));
plot([-1 -0.5,x],[0,0,y])
grid on