[petsc-users] Combine DM and FFTW

[Gerhard Ungersbäck]

Hello,


I want to solve a time dependent differential equation in 3D (Scalar field theory in Hamilton formulation) .

The crucial part is that at some time steps I need to FFT the 3D grid.


I have written a sequential code without petsc and now I would like to use petsc to get a parallel version.

I worked through the examples and now I understand DMDACreate and also the FFTW examples.


What is missing though is how I combine both!

DMDACreate takes care of ghost points and periodic boundary conditions. As far as I know FFTW requires each process to have a slab of the grid to work. I know how to create this grid with DMDACreate. Normally I would proceed by creating a global vector by DMCreateGlobalVector. But this vector needs then to be linked with fftw arrays. How does this work?

Or should I first allocate local memory for fftw and then somehow stitch them together to form a global petsc vector?


Thanks

best, gerhard

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20210910/eadee1b2/attachment.html>