Anton Leykin

(I think I converted it back to "Draft".) A quick comment on what seems to be the main issue with this PR for @mahrud. What would work is just simple...

@DanGrayson and @mahrud, I pushed a commit that has a change that makes it possible to run `M2` both with `mpirun` and without. It builds for me with `autotools` and...

> I think you should wrap things like `#include ` with a macro that checks if MPI is being used. We probably should just require MPI at build time. The...

> Even if you want the standard distribution to be MPI-capable (which is going to be difficult with brew and potentially also debian, since typically MPI-capable binaries are distributed in...

@mahrud, I've encapsulated all MPI-related code with macros, so ubuntu _non-MPI_ builds go through... but I don't understand why the _MPI_ build fails now. @DanGrayson, could you glance at `M2/configure.ac`?...

> @mahrud, I've encapsulated all MPI-related code with macros, so ubuntu _non-MPI_ builds go through... but I don't understand why the _MPI_ build fails now. I'll need some help with...

Everything is fine with `openmpi`, but there is an obstacle with `mpich`: there is no analog ot variable `OMPI_COMM_WORLD_RANK` (used, e.g., in M2/Macaulay2/bin/main.cpp). Is there any way to know if...

> Looking online, one suggestion seems to be to use the function `MPI_Comm_rank` instead, is that the same? Well, probing the environment variable was a way to determine if the...

> Even if you want the standard distribution to be MPI-capable (which is going to be difficult with brew and potentially also debian, since typically MPI-capable binaries are distributed in...

I had success building this on Fedora 34. It still segfaults on Ubuntu.