MATLAB自定义函数拟合fit

   
   
   
   

    
    
    
    

     
     
     
     

      
      
      
      

     
     
     
     
     
     
     
     

      
      
      
      

       
       
       
       %自定义拟合函数f(t)=a*
       
       
       
       cos(k*t)*
       
       
       
       exp(w*t)
      
      
      
      
     
     
     
     
    
    
    
    

     
     
     
     

      
      
      
      

     
     
     
     
     
     
     
     

      
      
      
      

       
       
       
       clc,clear
      
      
      
      
     
     
     
     
    
    
    
    

     
     
     
     

      
      
      
      

     
     
     
     
     
     
     
     

      
      
      
      

       
       
       
       syms t
      
      
      
      
     
     
     
     
    
    
    
    

     
     
     
     

      
      
      
      

     
     
     
     
     
     
     
     

      
      
      
      

       
       
       
       x=[
       
       
       
       0;
       
       
       
       0.4;
       
       
       
       1.2;
       
       
       
       2;
       
       
       
       2.8;
       
       
       
       3.6;
       
       
       
       4.4;
       
       
       
       5.2;
       
       
       
       6;
       
       
       
       7.2;
       
       
       
       8;
       
       
       
       9.2;
       
       
       
       10.4;
       
       
       
       11.6;
       
       
       
       12.4;
       
       
       
       13.6;
       
       
       
       14.4;
       
       
       
       15];%列向量
      
      
      
      
     
     
     
     
    
    
    
    

     
     
     
     

      
      
      
      

     
     
     
     
     
     
     
     

      
      
      
      

       
       
       
       y=[
       
       
       
       1;
       
       
       
       0.85;
       
       
       
       0.29;
       
       
       
       -0.27;
       
       
       
       -0.53;
       
       
       
       -0.4;
       
       
       
       -0.12;
       
       
       
       0.17;
       
       
       
       0.28;
       
       
       
       0.15;
       
       
       
       -0.03;
       
       
       
       -0.15;
       
       
       
       -0.071;
       
       
       
       0.059;
       
       
       
       0.08;
       
       
       
       0.032;
       
       
       
       -0.015;
       
       
       
       -0.02];
      
      
      
      
     
     
     
     
    
    
    
    

     
     
     
     

      
      
      
      

     
     
     
     
     
     
     
     

      
      
      
      

       
       
       
       f=fittype(
       
       
       
       'a*cos(k*t)*exp(w*t)',
       
       
       
       'independent',
       
       
       
       't',
       
       
       
       'coefficients',{
       
       
       
       'a',
       
       
       
       'k',
       
       
       
       'w'});  %fittype是自定义拟合函数
      
      
      
      
     
     
     
     
    
    
    
    

     
     
     
     

      
      
      
      

     
     
     
     
     
     
     
     

      
      
      
      

       
       
       
       cfun=fit(x,y,f) %根据自定义拟合函数f来拟合数据x，y
      
      
      
      
     
     
     
     
    
    
    
    

     
     
     
     

      
      
      
      

     
     
     
     
     
     
     
     

      
      
      
      

       
       
       
       xi=
       
       
       
       0:
       
       
       
       0.1:
       
       
       
       20;
      
      
      
      
     
     
     
     
    
    
    
    

     
     
     
     

      
      
      
      

     
     
     
     
     
     
     
     

      
      
      
      

       
       
       
       yi=cfun(xi);
      
      
      
      
     
     
     
     
    
    
    
    

     
     
     
     

      
      
      
      

     
     
     
     
     
     
     
     

      
      
      
      

       
       
       
       plot(x,y,
       
       
       
       'r*',xi,yi,
       
       
       
       'b-');
      
      
      
      
     
     
     
     
   
   
   
   
   
   
   
   

 

结果：

cfun = 


     General model:
     cfun(t) = a*cos(k*t)*exp(w*t)
     Coefficients (with 95% confidence bounds):
       a =      0.9987  (0.9836, 1.014)
       k =       1.001  (0.9958, 1.006)
       w =     -0.2066  (-0.2131, -0.2002)

文章转自：https://blog.csdn.net/mlp750303040/article/details/77651124