Fix issue with calculation of standard deviation at first point
Fix issue with calculation of standard deviation at first point

dariomangoni/chrono,projectchrono/chrono,Milad-Rakhsha/chrono,rserban/chrono,dariomangoni/chrono,amelmquist/chrono,Milad-Rakhsha/chrono,dariomangoni/chrono,projectchrono/chrono,rserban/chrono,rserban/chrono,amelmquist/chrono,rserban/chrono,armanpazouki/chrono,dariomangoni/chrono,amelmquist/chrono,dariomangoni/chrono,rserban/chrono,Milad-Rakhsha/chrono,Milad-Rakhsha/chrono,amelmquist/chrono,projectchrono/chrono,Milad-Rakhsha/chrono,amelmquist/chrono,projectchrono/chrono,projectchrono/chrono,armanpazouki/chrono,armanpazouki/chrono,armanpazouki/chrono,rserban/chrono,armanpazouki/chrono,projectchrono/chrono,amelmquist/chrono,armanpazouki/chrono,dariomangoni/chrono,rserban/chrono,Milad-Rakhsha/chrono