results = [ 0 15202;
            4 13136;
           -3 15162;
           -5 12091;
           -6 10026;
           -8 4215;
          -10 131];
      
errorbar(results(:,1),results(:,2),sqrt(results(:,2)),'o','markersize',10);

% Parabolic fit
function_parabola = @(x,a) a(1)*(x-a(2)).^2+a(3);
a0 = [-16000/100 1 16000];
sgn=0; dYda={@(x,a) 1};
[a,aerr,chisq,yfit,corr] = levmar(results(:,1),results(:,2),sqrt(results(:,2)),...
                                    function_parabola,a0,dYda,sgn);
hold on;
plot(results(:,1),yfit,'r','linewidth',2);