First, power operator ('**' and '@') is a special enhancement of cint for
convenience of scientific calculation. Standard C/C++ does not have this
operator.
The way it is implemented in cint is
left ** right => exp(right*log(left))
So, when you have left==0, log(0.0) behaves differently on each system.
I should have detect left==0 and left<0.
Masaharu Goto