If you like Python, Theano may be useful to you (haven't actually tried it):

http://deeplearning.net/software/theano/

Theano is a Python library that allows you to define, optimize, and evaluate mathematical expressions involving multi-dimensional arrays efficiently. Theano features:

- tight integration with numpy

- transparent use of a GPU

- symbolic differentiation

- speed and stability optimizations

- dynamic C code generation

- extensive unit-testing and self-verification