3.txt

包括牛顿法

>>   x=[-5:0.5:5];
y=1./(1+x.^2);
xh=[-5:0.125:5];
yh=langrange(x,y,xh);
 x=xh;
y=1./(1+x.^2);
 plot(xh,yh,'r--',x,y)






>>  x=[-5:0.5:5];
y=1./(1+x.^2);
a=lagran(x,y)
a =
  Columns 1 through 11 
    0.0000   -0.0000   -0.0000   -0.0000    0.0000   -0.0000   -0.0002   -0.0000    0.0031   -0.0000   -0.0251
  Columns 12 through 21 
    0.0000    0.1263    0.0000   -0.3916   -0.0000    0.7534   -0.0000   -0.9657   -0.0000    1.0000
xh=[-5:0.125:5];
yh=langrange(x,y,xh);
x=xh;
y=1./(1+x.^2);
plot(xh,yh,'r--',x,y)