% dati=[UT m r delta]
dati=[ 4.01   11.4    1.987    1.249  
       5.00   11.5    1.981    1.252  
       9.02   11.5    1.958    1.266  
       10.02  11.3    1.952    1.270  
       25.03  11.5    1.865    1.335  
       7.07   11.3    1.809    1.382  
       14.03  11.5    1.772    1.415  
       30.05  11.0    1.693    1.487  
       3.05   11.1    1.674    1.504  
       10.06  10.9    1.643    1.532  
       26.07  10.7    1.582    1.592  
       1.08   10.6    1.566    1.610  
       8.07   10.7    1.545    1.634  
       26.09  10.8    1.507    1.696 
       2.10   10.5    1.498    1.721
       6.09   10.4    1.495    1.736];
UT=dati(:,1);m=dati(:,2);r=dati(:,3);delta=dati(:,4);
% g+x*log(r)=m-5*log(delta), DETERMINARE g,x. 
% phi1(x)=1, phi2(x)=log(r), c1=g, c2=x.
V=[ones(size(UT)) log10(r)]; y=m-5*log10(delta); 
c=V\y;
hold on;
plot(r,y,'ro','MarkerSize',6,'MarkerEdgeColor','k','MarkerFaceColor','c');
plot(r,c(1)+c(2)*log10(r),'k-','LineWidth',2);
axis square
hold off;
format long e; c, [m-5*log10(delta) V*c]