expfitxy.m

fit programme for a serials of data

function estimates=expfitxy(x,y)
%input x is 1-by-N vector
%      y is 1-by-N vector
%output a is the coeficient of fitting formula y=a*exp(bx)
model=@expxy;
[estimates]=fminsearch(model,rand(1,2));
%define the function of condition for fitting formula
function f=expxy(params)
n=length(x);
f=0;
f1=@(x1) params(1)*exp(params(2)*x1);
for i=1:n
    f=f+(f1(x(i))-y(i))^2;
end
end
end