Installation

Using pre-built libraries

The easiest way to install the package is:

julia> ]
(@v1.12) pkg> add PETSc

which will install a pre-built PETSc library (PETSc_jll) as well as MPI.jl on your system. This will work both in serial and in parallel on your machine.

Windows Users

Since PETSc_jll 3.25.4 the Windows binaries are built with MPI (MicrosoftMPI_jll), and PETSc.jl runs natively on Windows in serial and in parallel; the test suite, including the MPI tests, runs there in CI. One limitation of PETSc 3.25.x on Windows: Tao objects can only be created before the first PETSc.finalize, see PETSc.tao_usable_after_reinitialize(). The Windows Subsystem for Linux remains an alternative if you need a custom PETSc build.

One `PetscInt` width per process

PETSc.petsclibs holds the four scalar variants (Float64, Float32, ComplexF64, ComplexF32) of one integer width, Int64 by default. The Int64 and Int32 builds of PETSc_jll link external packages (HYPRE, SuperLU_DIST) that export identical symbols with different integer ABIs, so both widths cannot be loaded into one process safely. To use the Int32 libraries instead:

using PETSc
PETSc.set_petscint!(Int32)   # stored in LocalPreferences.toml; restart Julia

Using a custom PETSc build

Sometimes, you may be interested in a PETSc installation that comes with additional external packages, or that you compiled yourself. Ensure the library is compiled as a dynamic (not static) library.

Use set_library! to configure the path once — it is stored in LocalPreferences.toml and no environment variables are needed afterwards:

using PETSc
PETSc.set_library!(
    "/path/to/custom/libpetsc.so";
    PetscScalar = Float64,
    PetscInt    = Int64,
)
# Restart Julia — PETSc_jll is not loaded and your library is used automatically.

To revert to the bundled binaries: PETSc.unset_library!().

To check what is currently configured: PETSc.library_info().

For a one-off session without changing persistent settings, use the PetscLibType constructor directly:

petsclib = PETSc.LibPETSc.PetscLibType("/path/to/custom/libpetsc.so";
                              PetscScalar=Float64, PetscInt=Int64)
PETSc.initialize(petsclib, log_view=true)
# ... your code ...
PETSc.finalize(petsclib)

HPC systems

On many high-performance clusters, you will need to use the cluster's MPI installation. There are a number of options to do so - see the Running on HPC Systems page for details.