利用数学知识分析1979至2009年我国GDP增长趋势，并利用matlab建立模型预测GDP增长，并给出预测的可信度。

clc;
x=1978:1:2007;
y=[3645.2,4062.6,4545.6,4891.6,5323.4,5962.7,7208.1,9016.0,10275.2,12058.6,15042.8,16992.3,18667.8,21781.5,35333.9,48197.9,60973.7,71176.6,78973.0,84402.3,89677.1,99214.6,109655.2,120332.7,135822.8,159878.3,183217.4,211923.5,257305.6,300670.0];
y0=[]
y=[y]
t=linspace(1978,2010,20);
p=polyfit(x,y,10);
z=polyval(p,t);
holdon
plot(x,y,'b*')

plot(t,z,'r');
plot(t,z,'r*');
gridon;
holdoff

ys=polyval(p,[2008:2010]);
fprintf('2008-2010\n');
fprintf('GDP:%d\n',ys');