DOLFINx-Adjoint

DOLFINx-Adjoint is an algorithmic differentiation (AD) framework for DOLFINx. It allows you to automatically compute the gradients and Hessians of PDE-constrained optimization problems and track your computational graphs through the pyadjoint backend.

Read the Latest Documentation here.

Note for Legacy FEnICS Users: If you are using the legacy FEnICS (dolfin) library, please refer to the original dolfin-adjoint repository. This repository (DOLFINx-Adjoint) is built specifically for the modern DOLFINx environment and is currently under active development. It is intended to eventually support the same comprehensive feature set and capabilities as the legacy version.

Features

• Automated Adjoints: Seamlessly derive discrete adjoint models from DOLFINx forward models.

• Overloaded API: Swap out standard dolfinx calls with their dolfinx_adjoint equivalents (e.g., Function, Constant, LinearProblem, NonlinearProblem, assemble_scalar) to automatically record the computational tape.

• Optimization: Seamless integration with PDE-constrained optimization frameworks like Moola or SciPy via pyadjoint.ReducedFunctional.

Installation

Dependencies

DOLFINx-Adjoint requires DOLFINx (>=0.11.0) and pyadjoint-ad.

via pip

The main way to install the package is via pip:

python3 -m pip install dolfinx-adjoint

via conda

You can also install dolfinx-adjoint via conda which also comes with DOLFINx

conda install -c conda-forge dolfinx-adjoint

Development Install

To install the latest development version directly from the repository, use:

python3 -m pip install git+[https://github.com/scientificcomputing/dolfinx-adjoint.git](https://github.com/scientificcomputing/dolfinx-adjoint.git)

If you plan to actively modify the code, clone the repository and install the optional dependencies for testing, development, and documentation generation:

git clone [https://github.com/scientificcomputing/dolfinx-adjoint.git](https://github.com/scientificcomputing/dolfinx-adjoint.git)
cd dolfinx-adjoint
python3 -m pip install -e ".[all]"

Quick Start

Using dolfinx_adjoint is designed to be as close to standard dolfinx syntax as possible. Here is a brief overview of how to track a parameter and assemble an objective functional:

import dolfinx
from mpi4py import MPI
import pyadjoint
import ufl
import dolfinx_adjoint

# Create mesh and function space
mesh = dolfinx.mesh.create_unit_square(MPI.COMM_WORLD, 10, 10)
V = dolfinx.fem.functionspace(mesh, ("Lagrange", 1))

# Use dolfinx_adjoint overloaded types
# This ensures operations are tracked on the pyadjoint tape!
f = dolfinx_adjoint.Function(V, name="Control")
f.interpolate(lambda x: x[0] + x[1])  # Initial guess for control
uh = dolfinx_adjoint.Function(V, name="State")

# Define UFL forms for a simple Poisson problem: - \Delta u = f
u, v = ufl.TrialFunction(V), ufl.TestFunction(V)
a = ufl.inner(ufl.grad(u), ufl.grad(v)) * ufl.dx
L = f * v * ufl.dx

# Set up Dirichlet boundary condition (u = 0 on boundary)
mesh.topology.create_connectivity(mesh.topology.dim - 1, mesh.topology.dim)
exterior_facets = dolfinx.mesh.exterior_facet_indices(mesh.topology)
exterior_dofs = dolfinx.fem.locate_dofs_topological(V, mesh.topology.dim - 1, exterior_facets)
bc = dolfinx.fem.dirichletbc(dolfinx.default_scalar_type(0.0), exterior_dofs, V)

# Use overloaded solvers
problem = dolfinx_adjoint.LinearProblem(a, L, u=uh, bcs=[bc])
problem.solve()

# Define a desired temperature profile 'd' and regularization parameter 'alpha'
x = ufl.SpatialCoordinate(mesh)
d = ufl.sin(ufl.pi * x[0]) * ufl.sin(ufl.pi * x[1])
alpha = dolfinx.fem.Constant(mesh, dolfinx.default_scalar_type(1e-6))

# Assemble the objective scalar using the overloaded assembly
J_symbolic = 0.5 * ufl.inner(uh - d, uh - d) * ufl.dx + 0.5 * alpha * ufl.inner(f, f) * ufl.dx
J = dolfinx_adjoint.assemble_scalar(J_symbolic)

# Create a ReducedFunctional for optimization
control = pyadjoint.Control(f)
Jhat = pyadjoint.ReducedFunctional(J, control)

# Evaluate gradient
gradient = Jhat.derivative()

For more comprehensive examples, such as solving the optimal control of the Poisson equation or time-distributed control problems, check out the demos/ directory or the online documentation.

Development and Testing

Code formatting is enforced via ruff and type-checking via mypy. To set up your local development environment:

# Install development dependencies
python3 -m pip install -e ".[dev,test]"

# Run formatting checks
ruff check .
ruff format --check .

# Run type checking
python3 -m mypy .

# Run tests
python3 -m pytest -vs tests/

License

MIT License. See LICENSE for more details.