function uncertain_statistics_by_principle_of_least_squares
x = [1,2,3,6,7,8];
alpha = [0.15, 0.45, 0.90, 0.85, 0.60, 0.20];
mu = @(a,x) (x>=a(1)).*(x<=a(2)).*(x-a(1))./(a(2)-a(1))+(x>a(2)).*(x<a(3))...
    +(x>=a(3)).*(x<a(4)).*(a(4)-x)./(a(4)-a(3));

error = 100;
for round=1:1:100
    for i=1:1:4
        a_initial(i) = unifrnd(0,9);
    end
    a_initial = sort(a_initial);
    [p,r] = lsqcurvefit(mu,a_initial,x,alpha);
    if error > r
       parameter = p;
       error = r;
    end
    round
    parameter
    error
end
plot(x,alpha,'*');
hold on;
ezplot(@(x) mu(parameter,x),[0,9]);
end