mathanalysis301.m

来自「数值分析的实验程序」· M 代码 · 共 27 行

i=0:10;
x=-1+0.2*i;
fx=1./(1+25*(x.^2));
figure;
plot(x,fx,'r*');
grid on;
hold on;
xx=-1:0.01:1;
l=zeros(length(i),length(xx));
ffx=l;
p=l;
q=zeros(length(x),1);
for i=1:11
    for j=1:11
        p(j,:)=xx-x(j);
    end
    p(i,:)=[];
    p=prod(p);
    q=(x(i)-x)';
    q(i)=[];
    q=prod(q);
    l(i,:)=p./q;
    ffx(i,:)=l(i,:)*fx(i);
end
ffx=sum(ffx);
plot(xx,ffx);
title('Runge现象');