Introduction to DOLFINx

We start by importing DOLFINx, and check the version and git commit hash

import dolfinx

print(
    f"You have DOLFINx {dolfinx.__version__} installed, "
    "based on commit \nhttps://github.com/FEniCS/dolfinx/commit/"
    f"{dolfinx.common.git_commit_hash}"
)

You have DOLFINx 0.9.0 installed, based on commit 
https://github.com/FEniCS/dolfinx/commit/4116cca8cf91f1a7e877d38039519349b3e08620

Using a ‘built-in’ mesh

In DOLFINx, we do not use wildcard imports as we used to in legacy DOLFIN, ie

from dolfin import *

We instead import dolfinx.mesh as a module:

from mpi4py import MPI

import dolfinx

mesh = dolfinx.mesh.create_unit_square(MPI.COMM_WORLD, 10, 10)

Interface to external libraries

We use external libraries, such as pyvista for plotting.

import pyvista

import dolfinx.plot

topology, cells, geometry = dolfinx.plot.vtk_mesh(mesh)
grid = pyvista.UnstructuredGrid(topology, cells, geometry)

We add settings for both static and interactive plotting

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pyvista.start_xvfb(0.5)

plotter = pyvista.Plotter(window_size=(600, 600))
renderer = plotter.add_mesh(grid, show_edges=True)

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# Settings for presentation mode
plotter.view_xy()
plotter.camera.zoom(1.35)
plotter.export_html("./mesh.html")

Interactive plot

We can get interactive plots in notebook by calling.

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%%html
<iframe src='./mesh.html' width="610px" height="610px">></iframe>  <!--  # noqa, -->