Hi d_stranz !

Thanks for your helpful answer.

My point was that an exact value of 0 is problematic, since log(0) -> minus infinity while log (1E-6) = -6. So a value close to zero, but not exactly 0 would not be a problem. So I wanted to eliminate the exact 0 value.
I'll do a test with your suggested solution to see how the scaling behaves.
Now for the "mutable" attribute, I learned something helpful that I did not know. I'll do some test using it as well.
Thanks and Happy easter !