What it is: A C++ software library supporting the creation of finite element codes and an open community of users and developers. (About deal.II)
Mission: To provide well-documented tools to build finite element codes for a broad variety of PDEs, from laptops to supercomputers. (deal.II documentation)
Vision: To create an open, inclusive, participatory community providing users and developers with a state-of-the-art, comprehensive software library that constitutes the go-to solution for all finite element problems. (Participate in deal.II)
Download
deal.II is open source and available for free!
Documentation
deal.II has extensive documentation and tutorials!
Participate
deal.II is a community project and welcomes participation!
Help
deal.II provides resources to learn and ask for help!
News
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2026/05/11: New tutorial programs step-98 and step-100: step-98 shows how to solve two-dimensional magnetostatic curl-curl problems, and step-100 applies a discontinuous Petrov-Galerkin method to the time-harmonic Helmholtz equation. There are also several new code gallery programs: Parallel implementation of heat equation, a transient heat equation solver with adaptive mesh refinement and a parallel solver; L-BFGS phasefield solver, a limited-memory BFGS monolithic solver for phase-field crack simulations; An agglomeration-based solver for the Poisson problem, a discontinuous Galerkin solver for the Poisson problem on general polytopal meshes generated through mesh agglomeration; An ALE approach for large-deformation thermoplasticity, an implementation of a large-deformation arbitrary Lagrangian-Eulerian finite-strain thermoplasticity solver; Parallel flow routing, a parallel solver for determining how much water is available at every point of a landscape; Parallel Vibroacoustic Solver, a parallel frequency-domain vibroacoustic solver calculating the sound transmission loss of a concrete wall; and Multilevel Monte Carlo for random Darcy flow, an implementation of a multilevel Monte Carlo method for random Darcy flow.
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2025/10/14: We wrote an editorial in SIAM News about mathematical software: Supporting computational science and engineering: How widely-used software in industrial and applied mathematics is created (pdf version).
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2025/07/22: Version 9.7.0 released: deal.II version 9.7.0 was released today. A full list of changes can be found here and a long description of changes is in the manuscript here. Download links are on the download page, or the release page on github.
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2025/05/31: The step-97 tutorial program, written by Siarhei Uzunbajakau, illustrates how to solve curl-curl problems.
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2025/05/07: The new step-93 tutorial program, written by Sam Scheuerman, demonstrates the use of degrees of freedom not associated with mesh nodes in an optimization problem.
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2025/03/03: SIAM/ACM Prize in Computational Science and Engineering: The principal developers of deal.II were awarded the SIAM/ACM Prize in Computational Science and Engineering "for their highly impactful library supporting finite element calculations. The software achieved a very high standard of software quality and modularity by providing packaged algorithms and data structures in a comprehensive and well-documented manner that enables and elevates whole communities to achieve more computationally advanced models than they could possibly otherwise." See here for the prize lecture.
Videos
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