www.gusucode.com > 关于海航matlab和lingo的训练题 > 人口拟合指数函数.m

    clear all 
x=[1971:1990];
y=[8.5229 8.7177 8.9221 9.0859 9.2420 9.3717 9.4974 9.6259 9.7542 9.8705 10.0072 10.1654 10.3008 10.4357 10.5851 10.7507 10.9300 11.1026 11.2704 11.4333]; 

fun=inline('exp(a(1)*t+a(2))','a','t')
a=nlinfit(x,y,fun,[0.01 -20])
xx=1970:1990;
yy=exp(a(1)*xx+a(2));
plot(x,y,'o',xx,yy)

z=log(y);
p=polyfit(x,z,1)
z1=polyval(p,x); 
y1=exp(z1);
figure
plot(x,y,'*',x,y1)