PostScript lacks a lot of basic operators such as tan, acos, asin, cosh,
sinh, tanh, acosh, asinh, atanh, exp (with e base). Also (oddly) cos and
sin use arguments in degrees. Pst-math provides all those operators in a
header file pst-math.pro with wrappers pst-math.sty and pst-math.tex. In
addition, sinc, gauss, gammaln and bessel are implemented (only
partially for the latter). pst-math is designed essentially to work with
pst- plot but can be used in whatever PS code (such as pstricks
SpecialCoor "!", which is useful for placing labels). The package also
provides a routine SIMPSON for numerical integration and a solver of
linear equation systems.