[dune-pdelab] Heat Equation in Parallel

[Christoph Grüninger]

Hi Afshin,
the CMake variable is called MPI_C_COMPILER, not MPI_CC_COMPILER.

Bye
Christoph

-- 
The method has been developed for use on a high-speed electronic
computer and would be impractical for hand-solution purposes.
                                           [Harlow & Welch 1965]