Tractrix curve, used for a horn/speaker & valve head

I used a tractrix curve to create the geometry used for horns/speakers & valve heads. Creating a valve or a horn will depend on what axis you revolve your function around. I used the equation I found on Wolfram http://mathworld.wolfram.com/Tractrix.html and substituted the hyperbolic functions for exponential ones (Solidworks doesn't have an input for them) http://en.wikipedia.org/wiki/Hyperbolic_function