func4p2.m

来自「数值分析最常用的四十种算法」· M 代码 · 共 12 行

%func4p2.m,求拟合多项式
x=linspace(1,12,12)
y=[12,234,34,-1,34,2,5,23,34,9,45,23]
p=polyfit(x,y,6)
xx=linspace(1,12,100)
yy=polyval(p,xx)
plot(xx,yy,'-')
f=polyval(p,x)
disp(abs(norm(y,inf)-norm(f,inf)))
%如用二次多项式拟合，the residue is (defined by infinite norm on those vector):135.5165，相当高。
%如提高为用六次多项式拟合，residue= 40.7265,比较精确；十次：residue=0.1571，相当低
%can also see the figure