> If I put in (expl .5 :base 10) why does Common Music return > 0.24025308??? This looks like a CLM envelope calculation -- see CLM's env.lisp under envelope-interp for the full formula which in this case is (/ (+ -1.0 (expt 10.0 .5)) (- 10 1)) There's also an instrument in that file showing how these values can be thought of in terms of e^-kt and so on.