视频

拓展学习

引例—人口增长预测问题

x=1790:10:2010;

y=[3.9,5.3,7.2,9.6,12.9,17.1,23.2,31.4,38.6, 50.2,63.0,76.0,92.0,105.7,122.8,131.7,150.7,179.3,203.2,226.5,248.7,281.4,308.7];

plot(x,y,'*');

p=polyfit(x,y,3);

polyval(p,2020)

plot(x,y,'*',x,polyval(p,x));

>> polyval(p,2016)

 

>> x=1950:10:2010;

>> y=[150.7,179.3,203.2,226.5,248.7,281.4,308.7];

>> p=polyfit(x,y,3)

 

>> p=polyfit(x,y,2);

>> plot(x,y,'*',x,polyval(p,x))

>> polyval(p,2016)

 

>> polyval(p,2020)

 

家庭储蓄规律问题

>> x=[0.6,1.0,1.4,1.8,2.2,2.6,3.0,3.4,3.8,4 ];

>> y=[0.08,0.22,0.31,0.4,0.48,0.56,0.67,0.75,0.8,1.0 ];

>> p=polyfit(x,y,1)

 

>> plot(x,y,'*',x,polyval(p,x))