chazhi1.m

1、掌握用MATLAB计算拉格朗日、分段线性、三次样条三种插值的方法

n=11;m=21;
x=-5:10/(m-1):5;
y=1./(1+x.^2);z=0*x;plot(x,z,x,y),gtext('y=1/(1+x^2)'),pause
x0=-5:10/(n-1):5;
y0=1./(1+x0.^2);
y1=lagr1(x0,y0,x);hold on,plot(x,y1,'r'),gtext('Lagr.'),pause,hold off,

y2=interp1(x0,y0,x);hold on,plot(x,y2,'b'),gtext('Pies.Lin.'),pause,hold off,

y3=interp1(x0,y0,x,'spline');hold on,plot(x,y3,'k'),gtext('Spline'),
s='      x         y        y1         y2        y3'
[x(11:21)' y(11:21)' y1(11:21)' y2(11:21)' y3(11:21)']