runge.m

比较三次样条插值和拉格朗日插值多项式对runge函数插值的效果并作图解释

n=10;

m=1:n+1;

x1=2/n*(m-1)-1;

% x-range
xx=-1:.001:1;

y1=p(x1, r(x1), xx);
y2=spline(x1, r(x1), xx);
y=r(xx);

plot(xx, y1, '-r',xx, y, '-k',xx, y2, '-.y', x1, r(x1), '.b')
axis([-1, 1, -0.2, 1.4]);
legend('Lagrange多项式','Runge函数', '样条插值');