# Installation

## Using pip

You can use pip to install `petsc4py` and its dependencies (`mpi4py` is optional but highly recommended):

    $ python -m pip install [--user] numpy mpi4py  (or pip install [--user] numpy mpi4py)
    $ python -m pip install [--user] petsc petsc4py (or pip install [--user] petsc petsc4py)

## Using setuptools

You can also install dependencies manually and then invoke setuptools from the petsc4py source directory:

> $ python setup.py build $ python setup.py install

You may use the –install-lib argument to the install command to alter the site-packages directory where the package is to be installed.

## From PETSc source

If you already have downloaded PETSc source and have installed the dependencies of petsc4py, then to build the petsc4py module along with PETSc, add the –with-petsc4py=1 argument to the configure command when building PETSc:

> $ ./configure –with-petsc4py=1 $ make $ make install

This will install PETSc and the petsc4py module into the PETSc directory under the prefix specified to the PETSc configure command.

If you wish to make the module importable without having to set the PYTHONPATH environment variable, you may add a shortcut to the system-wide site-packages directory creating a special .pth file with exactly one line of Python code. This can be done by the following command, where the system-wide path is assumed to be /usr/lib/pythonX/site-packages (replace X with your python version):

> $ echo

>   “import sys, os;” “p = os.getenv(‘PETSC_DIR’);” “a = os.getenv(‘PETSC_ARCH’) or ‘’;” “p = p and os.path.join(p, a, ‘lib’);” “p and (p in sys.path or sys.path.append(p))” > /usr/lib/pythonX/site-packages/petsc4py.pth