Symbolic Math Library in C/C++/Obj-C

I am trying to implement a graphing calculator on the iPhone. I am looking for a library that can take strings of expressions or functions and let me manipulate them (find derivatives, intercepts, zeros, etc). Does anything like this exist?

Solutions Collect From Internet About “Symbolic Math Library in C/C++/Obj-C”

There’s GiNaC for C++. GPL-licensed and actively maintained, last update only a month ago. I found old links to many others that don’t seem to exist anymore; perhaps people simply found it easier to use GiNaC?