the RE was to represent Reynolds, it's not that exact notation i'm using, thanks a lot for the help!!!

the RE was to represent Reynolds, it's not that exact notation i'm using, thanks a lot for the help!!!

@Markiyan Hirnyk 
i'm assuming you mean something like this:

diff(log(Nu(Re,M,Tau)),log(M))

as i did an attempt to explain before, a derivative of the log of a function wrt to a log of one of the variables within that function.

thanks for taking the time.