matlab插值作业

自行编写如下的Lagrange插值函数

function y=lagrange(x0,y0,x);
n=length(x0);m=length(x);
for i=1:m
    z=x(i);
    s=0;
    for k=1:n
        p=1;
        for j=1:n
            if j~=k
               p=p*(z-x0(j))/(x0(k)-x0(j));
            end
        end
        s=p*y0(k)+s;
    end
    y(i)=s;
end

在命令窗口输入

g1=@(x) 1./(1+x.^2);
hold on
x0=-6:1:6;
y0=g1(x0);
x1=-6:0.1:6;
y1=lagrange(x0,y0,x1)
plot(x1,g1(x1),x1,y1)

在命令窗口输入

g1=@(x) 1./(1+25*x.^2);
hold on
x0=-6:1:6;
y0=g1(x0);
x1=-6:0.1:6;
y1=lagrange(x0,y0,x1)
plot(x1,g1(x1),x1,y1)