[Serious - programming] I need ideas for program features

[wossname]

I'm writing a command line app that solves mathematical equations.

I need you guys to tell me what kind of math operators you would like to have in such a program. I've already covered most of the obvious ones (plus, minus, divide etc.)...

Supported Operators (token names only, use -L switch to get verbose info):
------------------------------------------------------------------------------------
+       -       *       /       <       >       ==      !=      <=      >=
<<      >>      neg     int     abs     sign    mod     pow     sin     cos
tan     ln      log     exp     asin    acos    atan    sqrt    &&      ||
^^      ~~      imp     eqv     min     max     rint    rand    sum     prod
gcd     mean    stdv    dump    count   swap    swlt    swgt    fact    ?
npr     ncr

If any of you boffins can see anything that I've missed out on this list (that you would expect / want / think is cool) then please let me know, I want this to be a good all-round math tool.

Any suggestions will get you a mention in the credits. I'm probably going to put this project up on sourceforge at some point (its ansi C++ so it'll compile on any platform )

Please keep it serious. Thanks.