Version 1.0
===========

* 2007 Andrew Clausen has written an original code Deriv.R and Simplify.R
 distributed on his site https://andrewclausen.net/computing/deriv.html

* 2009-2-21 Mark Reid's patch

* 2014-12-10
 - Andrew Clausen passed the maintenance to Serguei Sokol
 - Serguei Sokol has fixed a bug in simplification of "a-b"
 - revamped the documentation and code as an R package
 - put the code to GitHub https://github.com/sgsokol/Deriv
 - submitted the package to CRAN
