newtondf2.m

牛顿插值法

function r=newtondf2(x,y)
    nx=length(x);
    for i=2:nx
        t=x(i)-0.1;
        if(i~=nx)
            for k=1:3
                x1(k)=x(i+k-2);
                y1(k)=y(i+k-2);
            end
            s=lagr(x1,y1,t);
        else 
            for k=1:3
                x1(k)=x(nx-3+k);
                y1(k)=y(nx-3+k);
            end
            s=lagr(x1,y1,t);
        end
        r(i-1)=(s-y(i))/(t-x(i));         
    end