clear all
t=[0 10 20 30 40 50 60]';
N=[5.31 7.24 9.64 12.87 17.07 23.19 31.44]';
X=[ones(size(t)) t]
c=X\log(N)
z=exp(X*c)

plot(t,N,'r*',t,z,'-ob')
xlabel('years after 1800')
ylabel('size in millions')
legend('data','fitted model')