matlab數據擬合

• cftool工具箱主要是針對數據擬合的。使用起來特別的強大，尤其對於數據的處理超級方便，可以直接對於數據擬合，並且可以預設各種的擬合方案。這裏注意的是非線性的也可以進行擬合，例如：冪律，高斯等等。

https://jingyan.baidu.com/article/6f2f55a16aba04b5b93e6cca.html   

https://blog.csdn.net/rayna00/article/details/45060237     

https://www.cnblogs.com/tensory/p/6590779.html

http://blog.sina.com.cn/s/blog_4d4afb6d0100t37n.html

• polyfit(x,y,n)。用多項式求過已知點的表達式，其中x爲源數據點對應的橫座標，可爲行向量、矩陣，y爲源數據點對應的縱座標，可爲行向量、矩陣，n爲你要擬合的階數，一階直線擬合，二階拋物線擬合，並非階次越高越好，看擬合情況而定。

https://blog.csdn.net/misayaaaaa/article/details/71156256

https://blog.csdn.net/wendingzhulu/article/details/43062845

• fittype。

http://www.javaxxz.com/thread-366786-1-1.html 

%fittype function
%for Y=wm1.*N./power(1+a1*N,b1);
%when 0<ab-a<1,there's a peak,up first and down secondly;
%when 1<ab-a,all down;
%when ab-a<0,all up.

wm1=5,a1=2,b1=1.1;
N = linspace(1,100);
Y = wm1.*N./power(1+a1*N,b1);
plot(N,Y)
myfittype = fittype('wm.*N./power(1+a*N,b)','dependent',{'Y'},'independent',{'N'},...
    'coefficients',{'wm','a','b'});
myfit = fit(N',Y',myfittype)
a=myfit.a
b=myfit.b
wm=myfit.wm
plot(myfit,N,Y)

• 非線性擬合lsqcurvefit、nlinfit、lsqnonlin

https://www.cnblogs.com/Juli016/articles/5211239.html

https://blog.csdn.net/u014356002/article/details/70242501

https://blog.csdn.net/huahua19891221/article/details/81841220

%lsqcurvefit function
wm1=50,a1=2,b1=2;
N=1:100;
Y=wm1.*N./power(1+a1*N,b1);
scatter(N,Y)
hold on;

a=[1 2 3];

f=@(a,x)a(1)*x./power(1+a(2)*x,a(3))


a=lsqcurvefit(f,a,N,Y)
x=1:100;
f2=a(1)*x./power(1+a(2)*x,a(3))
plot(f2)