polyfitxy.m

fit programme for a serials of data

function A=polyfitxy(x,y,m)
%input x is a 1*N vector 
%      y is a 1*N vector
%      m is the degree of the polynomial to be obtain
%output A is the coeficient of the polynomial
n=length(x);
f=zeros(n,m+1);
%fill the columns of f with the powers of x
for i=1:m+1
    f(:,i)=x.^(i-1);
end
%solve the linear system to obtain the coeficient of polynomial 
B=f'*f;
C=f'*y';
A=B\C;
end