Question

求助：利用matlab对x=[0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4]; y=[30 22.5 15 10.5 6.5 4.5 3 2.5 1.5];

对其进行二次曲线拟合，求代码及图形。跪谢了。

Answer 1

x=[0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4]; y=[30 22.5 15 10.5 6.5 4.5 3 2.5 1.5];cftool打开拟合界面，

结果：Linear model Poly2:
       f(x) = p1*x^2 + p2*x + p3
Coefficients (with 95% confidence bounds):
       p1 =       2.317  (1.841, 2.793)
       p2 =      -16.04  (-18.02, -14.06)
       p3 =       29.65  (27.95, 31.34)

Goodness of fit:
  SSE: 4.373
  R-square: 0.9945
  Adjusted R-square: 0.9927
  RMSE: 0.8537

图形如下

Answer 2

p = polyfit(x,y,2);
f= polyval(p,x);

plot(x,y,'o',x,f,'-')

追问

那数值怎么算啊

追答

p就是