[petsc-users] How to build FFTW3 interface?

[Smith, Barry F.]

https://bitbucket.org/petsc/petsc/pull-requests/1539/update-to-the-lastest-fftw-release/diff


> On Apr 11, 2019, at 6:49 PM, Sajid Ali via petsc-users <petsc-users at mcs.anl.gov> wrote:
> 
> Hi PETSc Developers, 
> 
> To run an example that involves the petsc-fftw interface, I loaded both petsc and fftw modules (linked of course to the same mpi) but the compiler complains of having no knowledge of functions like MatCreateVecsFFTW which happens to be defined at (in the source repo) petsc/src/mat/impls/fft/fftw.c. I don't see a corresponding definition in the install folder (I may be wrong, but i just did a simple grep to find the definition of the function I'm looking for and didn't find it while it was present in the header and example files). 
> 
> From previous threads on this list-serv I see that the developers asked users to use --download-fftw at configure time, but for users that already have an fftw installed, is there an option to ask petsc to build the interfaces as well (I didn't see any such option listed either here: https://www.mcs.anl.gov/petsc/documentation/installation.html or a variant in spack) ?
> 
> Also, could the fftw version to download be bumped to 3.3.8 (here : petsc/config/BuildSystem/config/packages/fftw.py) since 3.3.7 gives erroneous results with gcc-8. 
> 
> Bug in fftw-3.3.7+gcc-8 : https://github.com/FFTW/fftw3/commit/19eeeca592f63413698f23dd02b9961f22581803
> 
> 
> Thank You,
> Sajid Ali
> Applied Physics
> Northwestern University