From Mathematica 5.2 to Mathematica 14.1 and you cannot simplify the sum of logarithms
This does it:
Collect[NU, {a^4, b^4}, -FullSimplify[-#] &]
It is often difficult to bring a complicated expression into the exact form we wish.
There is no such command in the Mathematica 14.1 help documentation.
Where can I learn more about this type of command?
-FullSimplify [- #] &]
Thank you for your help...
TVM Gianluca...
