symbolic computation

Question

Does anyone know a good approach/libs for doing algebraic computations in C++?

I have an application being developed in c++ which needs to do algebraic computation. For now I built a C++ parser that accepts expressions in form of strings like "5 + (2 - MYFUNC(3))" which get tokenized into structs and then converted into postfix notation using the Shunting Yard algorithm and evaluated.

The MYFUNC in these expression are my own defined functions that may do some complex computations.

This is a high performance app, the expressions also have variables that are dynamically replaced with values and the expression is re-evaluated

e.g. var1 + (2 - MYFUNC(var2)) -> with var1 and var2 replaced by some values during the course of the run and re-evaluated

I'm using Linux and so far found Giac library but not sure if it's good, any feedback would be welcome.

How do people generally approach this problem? The main language in this case is C++.

Answer 1

Have a look on Bison and Flex Parser. The basic idea here is that a grammar file would be written and converted into C code which can be integrated into you application. Any book on Flex and Bison (http://www.amazon.com/Flex-Bison-Text-Processing-Tools/dp/0596155972) is good enough for initial reading.

May be this helps you.!

Answer 2

Probably the fastest way to handle this is to generate a compiled, optimized function at runtime for the defined function, and evaluate it for the different variable values that you may have. You can do this with LLVM, probably other tools.