Hi all

Maybe I'm just being slow but I can't figure out how to work out this differentiation:

d ln (p(r))

---------

d ln(r)

-where p(r) = A*(1+(r/c)^2)^(-3B/2), and A,B,c are known constants. (p(r) is a model for gas pressure in a big ball of gas, if anyone's wondering).

If it was d ln(p(r)) / dr, it wouldn't be a problem...

but I'm not even quite sure what it means to say "d ln(r)". Have never tried differentiating a function with respect to another function before.

Any help would be much appreciated

A link to an explanation of how to do this would be especially nice, couldn't find anything on Google...

-Daniel