fitting.m

数值分析中的数值逼近方法以及曲线拟合算法

function [Fy a]=Fitting(x,y,n)
%curve fitting, y=f(x) 
%Fy is the estimation of y at x
%a is the coefficients of poly
%n is the order
%Weight w==1;
n1=n+1;
Fy=zeros(n1,1);
Lox=length(x);
%Aa=d
A=zeros(n1,n1);
d=zeros(n1,1);
a=zeros(n1,1);
%compute the parameter
for i=1:n1
    d(i)=sum(y.*(x.^(i-1)));
    for j=1:n1
        A(i,j)=sum(x.^(i+j-2));
    end
end

%if(abs(det(A))<=10^(-3)) diap("check matrix");
%else
    a=inv(A)*d 
    tp=fliplr(a');
    Fy=polyval(tp,x);
%end