ViennaCL is a free open-source linear algebra library for computations on 
many-core architectures (GPUs, MIC) and multi-core CPUs. The library is 
written in C++ and supports CUDA, OpenCL, and OpenMP (including switches 
at runtime).

The highlights of the latest 1.7.x release family are:

* Fast sparse matrix-matrix multiplications, outperforming CUBLAS and MKL.
* Fine-grained parallel algebraic multigrid preconditioners for CPUs, Xeon 
    Phis, and GPUs.
* Fine-grained parallel incomplete LU factorization preconditioners for 
    CPUs, Xeon Phis, and GPUs.

WWW: http://viennacl.sourceforge.net/