On 26 August 2014 at 10:13 PDT, Bill Paxton wrote: > dt_div_dt_mass_loss > ! dt_mass_loss = -M/Mdot; only applies when Mdot < 0 Why the sign restriction on Mdot? Given the name it makes sense, but why not ,---- | dt_div_dt_mass_change | ! dt_mass_change = -M/abs(Mdot) `---- Josiah