I am a teacher of Numerical Analysis and one of my student noticed that the condition number of the 20x20 Hilbert matrix computed by his MATLAB is different from the one obtained by mine. The MATLAB command given is
clear; format long e; cond(hilb(20))
My result is
while the student's result is
I asked other students to try, and about ten of them got my result (2.1e+18) but one of them got another different result:
I know that the Hilbert matrix is terribly ill-conditioned, so very sensistive to even slighest changes in the algorithms, but I do not expect that different instances of MATLAB give different results. Any explanation? I have also collected the output of the ver command, but it is not very illuminating. Could you please try the experiment yourself?