%% Choose model
x = [0 3 6 9 12 15 18 21 24 27 30 33];
y = [50.6 46.8 43.2 40.0 37.0 34.2 31.6 29.2 27.0 25.0 23.1 21.4];
subplot(2,2,1)
loglog(x,y)
subplot(2,2,2)
semilogy(x,y)
subplot(2,2,3)
semilogx(x,y)
subplot(2,2,4)
plot(x,1./y)
%% Fit curve to data
figure
p = polyfit(x, log(y), 1);
m=p(1);
b=exp(p(2));
x1 = linspace(0,33);
y1 = b*exp(m*x1);
plot(x,y,'o',x1,y1,'-b')