v1.2.7
The fix in 1.2.6 is not good. The change from Simplify to FullSimplify
in num=Simplify[mat] will cause new problem.
((-I/2)*(-I + Sqrt[3]))/Sqrt[2]//FullSimplify will gives Root[1+2 #1^2+4 #1^4&,1]
Change back to Simplify. Add a judgement for the zero norm case to calculate Arg.