CHANGELOG.md

Changelog

This document describes the changes made to the project.

3.5.1 (August 21, 2026):

• Added jax dependency in .readthedocs.yaml.

Full Changelog: https://github.com/matnoel/EasyFEA/compare/v3.5.0...v3.5.1

3.5.0 (August 21, 2026):

• Added AlgoType.hht_newmark, the HHT-Newmark time-integration scheme of Doyen, Ern & Piperno (SIAM J. Sci. Comput. 33(1), 2011). Unlike the existing generalized-alpha-style AlgoType.hht, which blends mass, damping and stiffness all by (1-alpha), this keeps the mass term at the full step and only shifts the stiffness (internal force) and external load — the discretization the paper proves second-order and unconditionally stable for alpha in [0, 1/3]. beta and gamma are derived from alpha rather than left free, since the stability/accuracy proof only covers that specific pair.
• Added Models.HyperElastic.AutoDiff (issue #53): a hyperelastic law declared from its potential W(C) alone, differentiated by jax (pip install easyfea[jax]) instead of a hand-written Compute_dWde/Compute_d2Wde. Checked against every shipped law's own closed-form derivatives; see examples/Hyperelasticity/AutoDiffPotential.py.
• Examples: the cardiac elastodynamics examples (BiVentricular.py, MonoVentricular.py) now share their material setup through Get_material in examples/CardiacElastoDynamics/utils.py.

Full Changelog: https://github.com/matnoel/EasyFEA/compare/v3.4.1...v3.5.0

3.4.1 (August 18, 2026):

• Fixed the Python 3.9 import: FEM/_mesher.py used typing.ParamSpec, which needs 3.10, so import EasyFEA failed on 3.9 in 3.3.0 and 3.4.0.

Full Changelog: https://github.com/matnoel/EasyFEA/compare/v3.4.0...v3.4.1

3.4.0 (August 18, 2026):

• Renamed the 3.3.0 materials-with-history API (breaking, no aliases kept): Simulations.Behaviour is now Simulations.InElastic, Models.Behaviour is now Models.InElastic.Behavior, and Yield, IsotropicHardening, KinematicHardening, ViscoPlastic, ViscoElastic and MaterialPoint all moved under Models.InElastic. The examples moved from examples/Behaviour/ to examples/Inelasticity/.
• Fixed a division by zero in the spectral return at Gauss points where nothing flowed; it was masked out of the result but emitted RuntimeWarnings on every 3.3.0 solve.
• Examples: assertions now check only analytic, mesh-independent quantities; ThickCylinder runs one mesh and one pressure ramp instead of a refinement study; removed SpringBack, which had no closed form to check against.
• Docs: autodoc_default_options set "imported-members": False, which Sphinx reads as True since bool_option() maps any value to true, so every module documented the names it imported. Removed, together with the fifteen :exclude-members: lists that existed to undo it.

Full Changelog: https://github.com/matnoel/EasyFEA/compare/v3.3.0...v3.4.0

3.3.0 (August 17, 2026):

• Materials with history (issue #48)
  • Added a small-strain, quasi-static framework for materials whose stress depends on the history of strain — plasticity, viscoplasticity and viscoelasticity — with Simulations.Behaviour and Models.Behaviour. With no internal variables it reproduces Simulations.Elastic to machine precision.
  • A behaviour is assembled from independent pieces rather than chosen from a list: an elastic law, plus any of a yield surface (Models.Yield: von Mises, Hill, Drucker-Prager), isotropic hardening (Models.IsotropicHardening: linear, Voce, Swift), a back-stress (Models.KinematicHardening: Prager, Armstrong-Frederick, Chaboche), a rate law (Models.ViscoPlastic: Norton, Perzyna) and Maxwell branches (Models.ViscoElastic). Hardening lives in the free energy rather than inside the yield function, so N surfaces and M hardening laws are N + M objects instead of N × M.
  • Two local solvers, chosen automatically; solver="newton" forces the general one. The implicit solve advances every internal variable by backward Euler and solves one system per Gauss point over the state increments and dGamma, with the consistent tangent read off the converged local Jacobian. The spectral return applies when the yield surface is quadratic (phi^2 = sig:P:sig) with homogeneous C and no kinematic hardening or viscous branches: diagonalising C^1/2 P C^1/2 once per material reduces the local problem to one scalar unknown, for any linear elasticity rather than isotropic only. Where both apply they agree to machine precision on stress, state and tangent, which is a test.
  • Models.MaterialPoint drives a behaviour at a single Gauss point with no mesh and no solver, holding the un-driven components stress- or strain-controlled — the same code path assembly uses.
  • Behaviour.Integrate takes the total strain and, optionally, the strain the increment started from (epsOld), supplied by the solver and never stored, so the state stays exactly the history variables. This matches MFront's eto/deto, Abaqus' STRAN/DSTRAN and NEML's e_n, and leaves room for local sub-stepping.
  • _Elastic.Get_sqrt_C_S now handles a C of any shape, including material properties given per Gauss point, and computes the square root by a batched eigh rather than np.unique + sqrtm — faster even when only two distinct matrices exist. It also fixes a cache keyed on sqrt_C alone, which crashed after setting S, and a first call that returned the live cache where later calls returned a copy.
  • Added ten examples in examples/Behaviour/, each checked against a closed form rather than against itself: uniaxial hardening curves, the Bauschinger effect, Chaboche superposition, Prony relaxation and Norton creep, Hill's thick cylinder, elastoplastic beam bending and the shape factor 3/2, a 3D tensile specimen, springback, and a relaxing perforated plate.
• FeArray refactor (issue #52)
  • A field's tensor rank is now ndim - 2, always, and is never re-read from a shape coincidence: a (Ne, nPg) FeArray is a scalar field even when Ne, nPg and the tensor width collide. This fixes four separate places that each guessed a field from its shape, including reductions that read the result shape rather than the axis.
  • All override logic moved into __array_ufunc__ and __array_function__, as NumPy recommends, instead of also overriding operator special methods. out= / where= are stripped to stop the recursion they caused, and FeArray is stripped from arguments before delegating so np.einsum's optimize= path cannot re-enter the protocol.
  • FeArray.broadcast is the single entry point for lifting a constant to a field; Reshape_variable delegates to it. asfearray now refuses ndim < 2 rather than silently returning a plain array, and zeros / ones accept a shape tuple.
• Mesher and Geoms
  • Mesher: public 1D meshing, a geometry view on failure, a testable partitioner, and transfinite counts decided per curve and sized by the geometry that produced it.
  • Geoms: points are exposed as read-only views so a geometry cannot desync, and point-in-geometry questions are answered directly instead of re-derived.
  • Surface reconstruction now works for a mesh holding several groups of elements.
• Tags and mesh I/O
  • Tags are stored as node sets, each in its own gmsh entity. Previously gmsh:geometrical was left unset, so every element landed in entity 0 and every tag read back by Mesher.Mesh_Import_mesh covered the whole mesh. Tags are sorted on the numbers they contain, so V2 comes before V10.
  • Every tag now survives a round trip through meshio: EasyFEA_to_Gmsh writes gmsh:physical, reading picks that array rather than letting a zeroed gmsh:geometrical overwrite it, a name that is not P{i}/L{i}/S{i}/V{i} no longer raises, and an unnamed reference 0 no longer invents a tag on a mesh that had none.
• MPI
  • Save_Iter writes one file per rank, sliced to the local dofs.
  • Added reduction helpers, Calc_Energy and _globalElements; partition arrays are sorted and results are stored with the nodes they cover.
• HyperElastic: active_stress accepts a per-element or per-Gauss-point field, and speed/acceleration field accessors were added.
• _Eigen_values_vectors_projectors: uses np.divide for the guarded division.

Full Changelog: https://github.com/matnoel/EasyFEA/compare/v3.2.2...v3.3.0

3.2.2 (August 4, 2026):

• Generalized TimeQuadratureStressTensor to non-midpoint schemes via a coefK argument.
• Updated simu.Result for phasefield and hyperelastic simulations.

Full Changelog: https://github.com/matnoel/EasyFEA/compare/v3.2.1...v3.2.2

3.2.1 (August 3, 2026):

• Cached the global sparse-matrix assembly so repeated assemblies (every Newton iteration and time step) reuse a precomputed reduction map instead of rebuilding the CSR from scratch — element-agnostic, with results unchanged to floating-point round-off (~1e-16 relative).
  • Simulations/_simu.py: __Assemble_csr caches, per (dof_n, isMatrix, Ndof, contributing groups), a map from each element entry to its slot in the global CSR data (__Get_csr_map, via @cache_computed_values). The scatter then becomes a single np.bincount into scipy's own canonical pattern — about 13x faster than the previous csr_matrix((data, (rows, cols))) re-sort, cutting the MonoVentricular matrix-assembly time by ~40%. The map is stored as int32 and is rebuilt only when the groups / Ndof / dof_n change or the mesh is reset.
  • Simulations/_hyperelastic.py: the dynamic mass matrix thickness · ∫ρ N·N, constant across a solve, is now cached (__Mass_e, via @cache_computed_values) instead of rebuilt every Newton iteration; a heterogeneous (array) ρ falls back to a direct recompute.
  • examples/CardiacElastoDynamics/MonoVentricular.py: the constant Robin surface-penalty tangents (top / epi) are built once and reused (_Get_Robin_surface_penalty, via @cache_computed_values), leaving only the state-dependent residual contractions in the assembly loop.
  • The geometry-derived caches (CSR reduction maps and mass matrices) are cleared together on mesh change / _Gather, so they never go stale or accumulate across a remesh.
• The complete non-linear residual — internal, inertia and damping forces — is now assembled into F_e inside Construct_local_matrix_system, and NonLinear.KelvinVoigtDamping returns its viscous residual alongside the configuration tangent and damping matrix. For a non-linear problem the solver no longer re-adds the time-scheme history terms (−C·v_t, −M·a_t); a custom simulation must therefore return the complete residual −R(u) in the F_e slot. See the updated "create a custom simulation" and pipeline how-tos.
• NonLinear.TimeQuadratureStressTensor: updated the adaptive-quadrature convergence criterion.
• PyVista.Plot: added a scalar_bar_kwargs argument to customise the scalar bar.
• Updated the "create a geometry" how-to for the copy=True argument.

Full Changelog: https://github.com/matnoel/EasyFEA/compare/v3.2.0...v3.2.1

3.2.0 (July 29, 2026):

• Energy-conserving stresses for HyperElastic dynamics
  • The internal force can now be sampled by an energy-conserving stress, so a free (no external load, no damping) AlgoType.midpoint run keeps the total energy KE + W constant where the default pointwise stress drifts. HyperElastic.StressType and Solver_Set_Stress select pointwise (default), gonzalez, or quadrature; both non-default stresses require AlgoType.midpoint.
  • Operators/NonLinear.py: new GonzalezStressTensor — the energy-momentum discrete-gradient stress Ŝ = S̄ + α Δe, which conserves KE + W exactly, for any law, from a single stress evaluation.
  • Operators/NonLinear.py: new TimeQuadratureStressTensor — the PK2 stress averaged along the step's strain path ∫₀¹ ∂W/∂e(eⁿ + s Δe) ds, integrated by a Clenshaw-Curtis rule (__clenshaw_curtis); a discrete gradient up to the quadrature error, which converges spectrally in nPoints (1, 2, 3 recover the midpoint, trapezoid and Simpson rules). Intermediate nodes are _StrainPathState, a strain-only state no displacement produces.
  • Operators/NonLinear.py: new __AdaptiveTimeQuadratureStressTensor — passing quadTol instead of a fixed nPoints refines the rule element by element until each element's own integrated energy defect ∫ (S:Δe − ΔW)² dΩ ≤ quadTol² ∫ ΔW² dΩ is met, spending points only where the step is nonlinear; the per-step point count is saved to the results as quadNPoints.
  • Operators/NonLinear.py: new ActiveStressTensor — the fiber active stress τ (T̂ ⊗ T̂) is assembled by its own operator and no longer folded into Compute_dWde, which stays exactly ∂W/∂e (the invariant the energy-based schemes rely on).
  • Added the examples/Hyperelasticity/Hyperelas5.py example comparing the stress schemes on a free-vibrating cantilever (energy drift, cost, and adaptive point count).
• Updated the Newton-Raphson convergence options.
• PyVista._setCameraPosition: added bounds arguments.
• Updated examples/CardiacElastoDynamics/MonoVentricular.py and minor _group_elem.py cleanups.

Full Changelog: https://github.com/matnoel/EasyFEA/compare/v3.1.0...v3.2.0

3.1.0 (July 1, 2026):

• Contact (issue #47)
  • Added a frictionless penalty-contact framework for unilateral contact against a rigid obstacle, solved as a non-linear problem with Newton-Raphson.
  • Operators/NonLinear.py: new PenaltyContact operator returning the contact tangent/residual (K_e, F_e) from a precomputed signed normal gap gap_e_pg and outward unit normal normal_e_pg sampled at the contact-surface Gauss points.
  • FEM/_group_elem.py: added _GroupElem._Get_gap_and_normal, which projects the deformed contact-surface Gauss points onto a rigid obstacle to produce the gap and normal consumed by PenaltyContact.
  • Added examples in examples/Contact/.
  • Removed the obsolete examples/LinearizedElasticity/Contact1.py example.
• Cardiac elastodynamics (issue #42)
  • Added the BiVentricular example (examples/CardiacElastoDynamics/BiVentricular.py)
  • Exposed the viscoelastic (Kelvin-Voigt) arguments in the CardiacElastoDynamics constructor and updated its shared utils.py.
• Created a new LinearizedElasticity example according to discussion #49.
• FeArray: added a reshape override that preserves the (Ne, nPg) element/Gauss-point leading axes when possible and otherwise degrades to a plain ndarray, and exposed ravel as a reduction.
• Utilities/_tic.py: timing now uses MPI.Wtime when MPI is available and time.perf_counter otherwise, instead of time.time().
• NonLinear.FollowingPressure: updated the einsum contractions.
• PyVista.Plot_BoundaryConditions: added a opacity argument.
• _mesher._Organise_Surfaces: reworked the surface-organisation logic.
• Minor _group_elem.py and Normalize cleanups.

Full Changelog: https://github.com/matnoel/EasyFEA/compare/v3.0.0...v3.1.0

3.0.0 (June 24, 2026):

Breaking changes:

• Split the Display module into two focused modules, with no backward-compatibility shim (issue #46). Update from EasyFEA import Display to from EasyFEA import Matplotlib, Terminal and rename the calls accordingly.
  • Matplotlib (renamed from Display): all matplotlib plotting — Plot, Plot_Mesh, Plot_BoundaryConditions, Plot_Tags, Plot_Energy, Plot_Iter_Summary, the Movie_* functions, Save_fig, Init_Axes, the matplotlib re-exports, and the requires_matplotlib guard (e.g. Display.Plot becomes Matplotlib.Plot).
  • Terminal (new): console helpers MyPrint, MyPrintError, Section, and Clear (e.g. Display.Clear becomes Terminal.Clear).

Performance:

• Sped up FEM operator assembly, cutting the cardiac MonoVentricular matrix-assembly time by ~41% with results equivalent to within 1e-13; all changes are element-agnostic.
  • Operators/NonLinear.py and Operators/Bilinear.py: fused the einsum contractions (collapsing the Gauss-point sum and dropping the large intermediates); the geometric tangent now exploits the block structure Sig = I_dim (x) sig (textbook Ksigma = g (x) I_dim), removing the dense 9x9 Sig build and the wide contraction.
  • Models/HyperElastic/_laws.py (HolzapfelOgden): common-subexpression elimination of the isotropic/anisotropic terms, dropped the identically-zero dWdI{4,6,8} * d2I{4,6,8}dC contributions, and fibers are normalized once in the constructor.
  • Models/HyperElastic/_state.py: the state no longer re-normalizes directions (now pre-normalized by the material), and __Build_De is built loop-free.
  • Added the Normalize(array, axis=-1) free function to EasyFEA.FEM.

Examples:

• Migrated every example (Beam, CardiacElastoDynamics, DIC, Hyperelasticity, LinearizedElasticity, MachineLearning, Meshes, PhaseField, Thermal, WeakForms, HelloWorld) to the new Matplotlib / Terminal API (issue #46).

Documentation:

• Updated the README, the beginner's guide, and the how-to / API pages for the Matplotlib / Terminal split.
• Refreshed the "Create a custom simulation" guide for the multi-element-group Construct_local_matrix_system API (now returning {groupElem: (K_e, C_e, M_e, F_e)} over mesh.Get_list_groupElem(), with the Get_* integration helpers accessed on groupElem), added an "Extend an existing simulation" section based on the MonoVentricular example, and cross-linked the FEM Operators catalogue.

Other:

• Updated the zorder and alpha arguments in the matplotlib plotting functions.

Full Changelog: https://github.com/matnoel/EasyFEA/compare/v2.0.0...v3.0.0

2.0.0 (June 23, 2026):

Meshes can now contain several element groups of the same (main) dimension, so mixed-element meshes are supported end-to-end — for example a contour meshed with Mesh_2D([], ElemType.QUAD4) in https://easyfea.readthedocs.io/en/stable/examples/Meshes/Mesh2_2D.html that gmsh fills with QUAD4 + TRI3 (issue #44).

Breaking changes:

• mesh.groupElem, mesh.elemType, and mesh.connect now raise AmbiguousGroupError when more than one group shares the main dimension (they cannot return a single value for a mixed mesh). Iterate mesh.Get_list_groupElem(mesh.dim) instead.
• Removed mesh.Get_rows_e, mesh.Get_columns_e, and mesh.nPe; use the corresponding members on each groupElem (the assembly path already loops per group).
• Renamed Display.Plot_Result to Display.Plot.

Multi-element-type support (issue #44):

• Reworked the writers to loop over mesh.Get_list_groupElem(dim), concatenating per-element results in mesh.Ne order: Display.Plot, the PyVista export (MeshIO), Mesher.Save_Simu, and the Paraview VTU/PVTU export (both serial and MPI).
• Made the mesh utilities multi-group aware: Elements_Nodes, Evaluate_dofsValues_at_coordinates, Get_meshSize, Get_Quality, and the MPI _Gather (coordinates are now gathered across every group). The generic result path simu._Get_values and the per-element stress/strain computations now assemble per group via groupElem.Locates_sol_e.
• Updated the core Mesh functions and meshing helpers to operate on the list of element groups and removed the internal mesh.__groupElem shortcut.

Display:

• Refactored the Display functions; renamed Display.Plot_Result to Display.Plot and reworked Plot_Mesh together with the handling of the result, plotMesh, and plotDim arguments.

MPI:

• Improved MPI behavior in the simulations and in Solvers.py (issues #26 and #44).

Other:

• NonLinear.FollowingPressure: updated the argument order.
• Removed optimize="optimal" in EasyFEA/FEM/_linalg.py.
• Added the Homog5 example to the documentation gallery, added a mesh-creation assertion in _beam.py, and fixed documentation warnings.

Full Changelog: https://github.com/matnoel/EasyFEA/compare/v1.11.0...v2.0.0

1.11.0 (June 15, 2026):

• Created the EasyFEA.FEM.Operators module, gathering the element-level operators that integrate a form over the Gauss points (issue #43).
  • Bilinear: UV, GradUGradV, GradU_A_GradV, LinearizedElasticity, MassAlongNormal, and the beam operators BeamBending, BeamShear, BeamStiffness, BeamMass.
  • Linear: V.
  • NonLinear: SecondPiolaKirchhoffStressTensor, KelvinVoigtDamping, FollowingPressure.
  • Refactored the simulations to assemble their element matrices through these operators.
• Introduced finite-strain viscosity and active stress in hyperelasticity (issue #42).
  • Kelvin-Voigt viscosity material.eta (large-strain Σ_visco = η·Ė), delivered through NonLinear.KelvinVoigtDamping, which returns both the damping matrix and the configuration tangent so the gap is closed without touching the time-scheme coefficient mechanism.
  • Fiber active stress material.active_stress along a direction registered with material.Set_active_stress_vec.
• Added the CardiacElastoDynamics example (MonoVentricular.py): a passive + active hyperelastic left-ventricle simulation reproducing Benchmark i: monoventricular mechanics of the cardiac elastodynamics benchmark (Comput. Methods Appl. Mech. Engrg.), with analytic and cardiac_benchmark_toolkit (vtu) fiber/sheet sources (issue #42).
• Refactored Construct_local_matrix_system and made HyperElasticState operate on a groupElem; the velocity is now passed explicitly to KelvinVoigtDamping instead of being stored on the state (issue #44).
• Added FeArray reduction methods and an integrate helper, and fixed a FeArray.broadcast ambiguity on per-element tensors via tensor_ndim.
• Fixed a shared mutable-default-dictionary bug in the Save_Iter functions that leaked iteration keys across calls and across simulations in the same process.
• Fixed bugs in phaseField._Calc_Sigma_e_pg, in the LinearizedElasticity examples, in groupElem._Get_Mapping / Get_pointsInElem (local connectivity), and in the Mesher MPI partitioning (snapshot connectivity before gmsh.partition).
• Fixed an mpi4py deadlock on plain python and a petsc4py double-initialization warning.
• Updated Mesher.Mesh_Import_mesh to reconstruct physical groups from gmsh entities and to accept a meshOrder argument; renamed wedge to penta in MeshIO.DICT_ELEMTYPE_TO_ENSIGHT.
• Documentation: added an Operators section to the FEM API and a "from element operators to the global system" section to the solve-pipeline guide; improved the introduction docstrings of every simulation; referenced CardiacElastoDynamics in the docs and READMEs.

Full Changelog: https://github.com/matnoel/EasyFEA/compare/v1.10.1...v1.11.0

1.10.1 (May 31, 2026):

• Fixed flaky test_Evaluate_dofsValues_at_coordinates_2D and _3D: replaced the unseeded random-node sample with a vectorized assert_allclose over all nodes (tolerance now reflects Newton inverse-mapping precision).
• Loosened machine-precision tolerances in TOLS_TIP and TOLS_DISTRIB (beam tests) from 1e-12 to 1e-11 to absorb harmless float noise.
• Updated documentation and example READMEs to reference Timoshenko beams alongside Euler-Bernoulli, with a pointer to Beam2 as the worked Timoshenko example.

Full Changelog: https://github.com/matnoel/EasyFEA/compare/v1.10.0...v1.10.1

1.10.0 (May 31, 2026):

• Created euler_implicit and euler_explicit hyperbolic algorithms.
• Continued work on Timoshenko beams (issue #39).
  • Replaced Jouravski's formula with Cowper's (1966) shear correction factor in _Get_shear_correction_factor.
  • Prevented shear locking for Timoshenko elements.
  • Updated shear correction factor docstrings.
  • Updated links to fem object.
• Fixed bug in hyperelastic._Calc_W function.
• Created simu.__Get_Ndof function and refactored simu._Get_*_n functions to use it.
• Simplified simu._Solver_Apply_Dirichlet function.
• Removed _ScipyLinearDirect function.
• Updated the default element type in Mesh_Beams function.
• Improved Matrix System Solvers documentation in docs/api/simulations.md.

Full Changelog: https://github.com/matnoel/EasyFEA/compare/v1.9.2...v1.10.0

1.9.2 (May 21, 2026):

• Created the CiarletGeymonat hyperelastic law.
• Fixed bug for hht algorithm in simu._Solver_Evaluate_u_v_a_for_time_scheme function.
• Created simu.__Bc_check_inputs function.
• Updated the argument position in simu.Solver_Set_Hyperbolic_Algorithm.
• Improved FeArray functions.
• Updated the _Write_solution_file function in Vizir.py.

Full Changelog: https://github.com/matnoel/EasyFEA/compare/v1.9.1...v1.9.2

1.9.1 (May 5, 2026):

• Improved how invalid characters are handled by EasyFEA/Utilities/Display.py function
• Removed pyvista version restriction and close pyvista/pyvista#8628.
• Removed hard-coded elemType in EasyFEA/Utilities/MeshIO.py

1.9.0 (May 4, 2026):

• Worked on issue #38 and improved static and dynamic Euler-Bernoulli beam simulations.
  • Introduced new tests and examples.
  • Examples now compute Ty, Mz and N when needed.
  • Set scipy as the default solver for beam simulations.
  • Create beam.add_lineLoad override.
• Started working on timoshenko beams in #39.
• Refactored GroupElemFactory with GROUP_CLASS_MAP
• Removed bug in Display.Movie_Simu introduced in #21 updates.
• Updated simu.Result behavior for not implemented results.
• Updated parabolic and hyperbolic time schemes when the simulation is using Lagrange multipliers.
• Improved display function behavior with inDim calculation.
• Updated simu.Calc_Reaction and return just dofs values in seq mode.
• Removed MPI_COMM in solvers._PETSc function.
• Improved simu.__Bc_Integration_Dim function.
• Fixed bug in MeshIO._Set_Tags function.
• Updated PyVista.Plot_Tags function
• Created a mesh.Merge function,
• Updated tol to 1e-12 in tests/Models/phasefield_test.py
• Updated optionTex in EasyFEA/Utilities/Display.py
• Updated pyvista to version (<=0.47.3) until the following issue is fixed: pyvista/pyvista#8628

1.8.5 (April 22, 2026):

• Improved solver behavior when simulations are using Lagrange boundary conditions.
• Simplified homogenization examples.
• Set petsc4py options by default in EasyFEA/Simulations/_simu, even if petsc4py is not available.

1.8.4 (April 20, 2026):

• #26 Improved mpi behavior:
  • Removed coordGlob array in mesh and groupElem.
  • Add ghost cells and ghost points in EasyFEA/Utilities/Paraview.py
• Fixed a bug in Meshio._GroupElem_to_PyVista function.
• Updated phase field examples.
• Created Save and Load functions for mesh object.
• Created Folder_test.py

1.8.3 (April 7, 2026):

• Migrated CI/CD and ReadTheDocs to uv for dependency management.
• Improved performance of _phasefield.__Spectral_Decomposition in 2D and 3D.
• Fixed rounding errors in _phasefield.__Spectral_Decomposition in 3D.
• Updated mesher.Save_Simu function.
• Improved mesher._Mesh_Get_Mesh profiling (#26).

1.8.2 (April 1, 2026):

• Improved simu._Solver_Set_PETSc4Py_Options function (#26).
• Updated the meshSize in Hyperelasticity examples.

1.8.1 (March 29, 2026):

• Improved Sphinx documentation.
• Renamed isHollow to isFilled across all geometry classes (Domain, Circle, Points, Contour), with an inverted default value (False). Specifically, isHollow=True becomes isFilled=False, and isHollow=False becomes isFilled=True.
• Improved the CONTRIBUTING guide.
• Fixed a bug in simu.folder and simu.Load_Simu.

1.8.0 (March 28, 2026):

• Resolved issue #26: Implemented full MPI support for distributed-memory parallel simulations using petsc4py.
  • Created EasyFEA/Utilities/_mpi.py with MPI utility functions (Concatenate_array, Sync_dofsValues).
  • Added rank0_only decorator and applied it to public functions in Display, PyVista, and Paraview modules.
  • Implemented simu._Gather and mesh.Gather functions to assemble distributed results on rank 0.
  • Added Folder.Rank_Dir function for rank-specific output directories.
  • Refactored the Paraview module to handle MPI results with per-rank .vtu files.
  • Improved PETSc solver options and pipeline; set GAMG as the default preconditioner.
  • Fixed memory leaks in the PETSc solver using PETSc.garbage_cleanup().
  • Updated the Newton–Raphson algorithm for MPI context.
  • Fixed bugs in simu.Save_Iter, simu.folder setter, _mpi.Concatenate_array, and solver.__Get_unique_dofs.
• Improved Sphinx documentation by adding a comprehensive how-to section.
• Merged PR #36 with updates: Improved examples/README.rst.
• Resolved issue #37: Added examples in docstrings.
• Created MeshIO.Merge function to combine multiple meshes.
• Added simu.Get_dofs function.
• Exported AlgoType in EasyFEA/__init__.py.
• Improved FeArray implementation.
• Improved simu._Solver_Apply_Dirichlet and simu.__Solver_Get_Dirichlet_A_x functions.
• Updated simu.Results_Set_Iteration_Summary behavior.
• Improved EasyFEA/Models/_phasefield.py and related phase-field examples.
• Improved mesher._Mesh_Generate.
• Refactored EasyFEA/Utilities/_tic.py to prevent memory issues.
• Removed the numba optional dependency.
• Fixed a bug in PyVista.Plot_Elements.

1.7.4 (March 8, 2026):

• Removed additionalPoints from examples/LinearizedElasticity/Homog4.py.
• Added Git LFS tracking for *.png files.
• Resolved issue #8: Added DIC examples.

1.7.3 (March 4, 2026):

• Updated Sphinx Gallery and model viewer.
• Fixed a bug in the mesh.Get_Node_Values function when the mesh contains orphan nodes.
• Improved and closed issue #35: Export EasyFEA results to USD format.
• Added Git LFS tracking for *.msh files.
• Fixed periodic boundary conditions in Homog4.py and introduced Homog5.py.

1.7.2 (February 14, 2026):

• Updated the _requires module.
• Resolved issue #34 to enable export of EasyFEA results to GLB format.
• Resolved issue #35 to enable export of EasyFEA results to USD format.
• Implemented an interactive gallery using the GLB format and the model-viewer component.

1.7.1 (January 30, 2026):

• Updated the Mesh.Nodes_* methods.
• Removed the groupElem.assembly_e property.
• Added a SwapOrientation option for the crack plugin.
• Clarified the groupElem._Get_sysCoord_e method.
• Created the PyVista.Plot_Arrows function.
• Updated surface normals for 3D elements:
  • Ensured consistent coordinate usage across element groups.
  • Utilized all coordinates in the MeshIO.Surface_reconstruction function.
  • Guaranteed outward-facing normals for all mesh faces in groupElem._Get_sysCoord_e.
• Updated Sphinx documentation:
  • Updated docs/html_theme_options.
  • Reset Geoms instance numbering and ensured BUILDING_GALLERY is set to False during gallery construction.
  • Updated LaTeX options in the documentation.
  • Removed \begin{alignat} from .. math:: environments.
• Updated optional dependencies:
  • Marked meshio as an optional dependency.
  • Marked imageio as an optional dependency.
  • Added io to optional dependencies.
  • Added viz to optional dependencies.
  • Updated optional dependencies in .github/workflows/tests.yaml.
  • Marked matplotlib and pyvista as optional dependencies.

1.7.0 (January 18, 2026):

• Updated EasyFEA api and sphinx documentation.

1.6.5 (January 10, 2026):

• Fixed bug in mesh_test.py.
• Updated imageio[ffmpeg] to imageio-ffmpeg in README.
• Added tol parameter in groupElem._Get_coord_Near method.
• Removed jupyter and zip outputs from docs examples.
• Fixed issue #31: Created Folder.Results() function and removed Folder.RESULTS_DIR.
• Updated links and warnings in docstrings.
• Switched from reStructuredText to Markdown in Sphinx documentation.
• Added mathematical formulations for simulations.

1.6.4 (January 5, 2026):

• Updated sphinx documentation.
• Updated ElasOrthotropic implementation.
• Defined ElasOrthotropic.Walpole_Decomposition method.
• Updated how Walpole_Decomposition functions are checked during unitests.
• Create mesh.Calc_regulation_projector.
• Updated mpi4py and numba as optional dependencies.

1.6.3 (January 2, 2026):

• Updated the Result_in_Strain_or_Stress_field function and its calls to replace field_e with field_e_pg.
• Added Field.Evaluate_e and Field.Evaluate_n methods to evaluate functions on elements or nodes.
• Added the von_mises_stress function in examples/WeakForms/LinearElasticity1.py.
• Fixed a bug in the Display.Plot_Result function when nodeValues=False.
• Clarified the Mesher._Mesh_Get_Mesh function and moved the _gmsh_interface.py module to _gmsh.py.
• Began work on issue #26: Solve simulations using petsc4py and MPI.
• Added the Gauss._Gauss_factory_nPg function and refactored Gauss point construction.
• Updated the Paraview.__Make_pvd function to use relative paths for accessing VTU files.
• Improved the MeshIO module.
• Renamed mesh.coordGlob to mesh.coord.
• Created examples/LinearizedElasticity/Homog4.py.
• Implemented the ElasOrthotropic model.
• Fixed issue #27: Corrected bug in PhaseFieldSimu._Calc_Psi_Ext method.
• Updated iteration printing in Display, Paraview, and PyVista functions.
• Addressed issue #29: Clarified the Simu.add_pressureLoad() function.
• Updated the simu.add_neumann function.
• Resolved issue #28: Added topology optimization example.
• Enhanced the Sphinx documentation.

1.6.2 (November 20, 2025):

• Updated homogenization examples.
• Improved documentation.
• Removed pandas dependency.
• Enhanced Tic.Plot_History functions.
• Updated the mesh.Evaluate_dofsValues_at_coordinates function.
• Refactored mesh functions in _gmsh_interface.py.
• Updated functions in EasyFEA/fem/_forms.py used by EasyFEA/simulations/_weak_forms.py.

1.6.1 (November 9, 2025):

• Updated the thermal simulation description.
• Refactored the use of time schemes for nonlinear problems.
• Clarified the names and descriptions of the simulation solver functions.

1.6.0 (November 8, 2025):

• Updated the Display and PyVista functions.
• Updated the construction of dict_tags in the _Meshio_to_EasyFEA function.
• Improved the hyperelastic simulation to handle hyperbolic problems.
• Organized and enhanced the documentation scripts.
• Improved hyperelastic models for 2D simulations under the plane strain assumption.

1.5.5 (November 5, 2025):

• Updated the solver parameter in the phasefield model.
• Added an assertion in _Simu.Get_K_C_M_F to detect multiple problem types.
• Updated PositiveParameter to PositiveScalarParameter in some models #23.
• Renamed _pyVistaMesh to _pvMesh in EasyFEA/utilities/PyVista.py.
• Updated PyVista._setCameraPosition with its docstrings and modified how the function is called.
• Added the I6 and I8 invariants in EasyFEA/models/_hyperelastic.py.
• Added VectorParameter and _CheckIsVector in EasyFEA/utilities/_params.py.
• Updated the behavior of TensorProd and Project_Kelvin functions for FeArray.
• Updated vector checks in EasyFEA/models/_hyperelastic.py.
• Created the HolzapfelOgden hyperelastic law in EasyFEA/models/_hyperelastic_laws.py.
• Updated FEM solvers:
  • Updated the Newton_Raphson algorithm.
  • Removed the simu.solverIsIncremental option.
  • Updated newmark, midpoint, and hht acceleration formulations to displacement formulations.
  • Updated Set_Rayleigh_Damping_Coefs to ensure the matrix is updated in EasyFEA/simulations/_elastic.py.
  • Revised the use of the Newton_Raphson algorithm in nonlinear simulations.
  • Updated the Newton_Raphson algorithm to print the residual L2 norm (with applied boundary conditions).
• Updated the TensorProd function in EasyFEA/fem/_linalg.py.
• Updated hyperelastic chain rules to ensure cross-term derivatives used in d2W utilize tensor products.
• Refactored the HyperElastic static class into a HyperElasticState class for improved performance and code readability.
• Applied the cache_computed_values decorator to replace outdated caching methods in EasyFEA/fem/_group_elems.py and EasyFEA/models/_hyperelastic.py.
• Fixed a bug in the first derivatives of anisotropic invariants I4, I6, and I8.
• Fixed a bug in the penalization solver.
• Added the bulk modulus term to the MooneyRivlin hyperelastic law.
• Added the bulk modulus term to the Saint-Venant-Kirchhoff hyperelastic law.

1.5.4 (October 23, 2025):

• Fixed issue #23: Descriptors are now used to simplify property creation in classes.
• Fixed issue #24: Introduced the Construct_matrix_system function and removed all Assembly functions. This reduces the amount of code required for each simulation.
• Fixed a bug in the _Create_Lines dispatch methods.
• Updated the _Write_solution_file function in utilities.Vizir.py.
• Fixed a bug in Get_pointsInElem caused by nan values in normalized arrays.
• Added the mesh.Evaluate_dofsValues_at_coordinates function.
• Added the HolzapfelOgden hyperelastic law in the examples/HyperElastic/HyperElasticLaws.py script.
• Removed the useNumba property from simu and models.
• Removed the dim argument from the Thermal model.
• Updated functions in EasyFEA/utilities/_params.py.
• Clarified tests for phasefield.

1.5.3 (October 1, 2025):

• Added the I8 invariant to the examples/HyperElastic/HyperElasticInvariants.py script.
• Fixed issue #22: Implemented singledispatch methods in _gmsh_interface.py, geoms/_utils.py, _simu.py and PyVista.py to improve code readability.
• Introduced the BUILDING_GALLERY option and updated the Display.Clear function to ensure the Tic history is initialized when BUILDING_GALLERY = True.

1.5.2 (September 11, 2025):

• Fixed a bug in the Mesh.Translate, Mesh.Rotate, and Mesh.Symmetry functions.
• Added the MeshIO.EasyFEA_to_Ensight and MeshIO.Ensight_to_EasyFEA functions.
• Fixed a bug in the matrix order in the Paraview.Save_simu function.
• Added a depth option to the Folder.Dir function.
• Updated the docstrings for weak forms.
• Fixed a bug in the Vizir.__Write_HOSolAt_Solution function.
• Added a concatenate option to the Field.Get_coords function.
• Added the groupElem.Get_normals_e_pg function.
• Updated mesh.Get_normals to use the groupElem.Get_normals_e_pg function.
• Fixed the path used in the Sphinx documentation.
• Fixed a bug in Mesh.Nodes_Tags.

1.5.1 (July 23, 2025):

• Improved documentation by adding more animated GIFs
• Updated MeshIO.Surface_reconstruction.
• Updated Material.WeakForms docstrings.
• Fixed issue #21:
  • Clarified Display.py and PyVista.py modules.
  • Improved Plot_Tags functions.
• Improved mesh and element group tagging.
• Fixed bug in _Additional_Points().
• Switched GroupElemFactory _Create and Create.

1.5.0 (July 16, 2025):

• Updated Python version in README.md.
• Updated Display module according to modifications in #19.
• Updated Vizir module.
• Updated MeshIO docstrings.
• Fixed mypy and ruff type issues.
• Renamed linesVector_e to rowsVector_e and linesScalar_e to rowsScalar_e in simulations and group of elements.
• Fixed issue #20: Users can now perform finite element analysis by simply providing weak form functions.
  • Renamed Materials to Models.
  • Created Field, BilinearForm, LinearForm, Materials.WeakForms, and Simulations.WeakFormSimu.
  • Created 2 Poisson and 2 linear elasticity examples with tests.
• Improved the documentation by providing as many animated GIFs as possible.

1.4.8 (July 7, 2025):

• Updated meshio's fork dependency in pyproject.toml [dev].
• Fixed mypy types.

1.4.7 (July 7, 2025):

• Updated visualization modules: Vizir.py, PyVista, and Display.py.
• Added new topological information (Nedge, Nvolume) for each element group.
• Added surfaces and edges data for each element group.
• Created MeshIO.Surface_reconstruction() method.
• Added meshio tests covering surface reconstruction and import functionality.
• Updated meshio's fork dependencies in:
  • .github/workflows/tests.yaml
  • docs/requirements.txt
  • pyproject.toml [dev]
• Added MeshIO import functions in FEM API documentation.
• Improved convergence criteria in _Solver_Solve_NewtonRaphson.
• Updated mesh used in test_PhaseField function.
• Moved ModelType.Is_Non_Linear to simu._Solver_problemType_is_non_linear.

1.4.6 (July 2, 2025):

• Updated links in docs/index.rst and README.md.
• Renamed weightedJacobian_e_pg to wJ_e_pg in scripts.
• Updated Solvers.py dependencies.
• Reordered tensor ordering in Paraview.py.
• Fixed issue #17: Fixed Newton-Raphson algorithm and added a new hyperelastic example.
• Fixed issue #18: Updated MeshIO.py to import EnSight meshes.

1.4.5 (June 25, 2025):

• Fixed issue #16: Enabled Paraview functionality without a simulation object.
• Updated documentation links to reference external research projects.

1.4.4 (June 21, 2025):

• Fixed issue #15: You can now create meshes simply by using geometric objects.
• Enhanced docstrings, documentation and examples.

1.4.3 (June 16, 2025):

• Added an interface to Vizir (see issue #9).
• Applied black code formatting across the codebase (see issue #10).
• Integrated continuous integration using GitHub Actions (see issues #11, #13, and #14).
• Added comprehensive documentation (see issue #5).
• Fixed tkinter issue in CI for py3.12 on windows. (see: https://github.com/matnoel/EasyFEA/actions/runs/15673958144/job/44150031408)

1.4.2 (June 7, 2025):

• Direct dependency on meshio@ git+https://github.com/matnoel/meshio.git cannot be included in PyPI.

1.4.1 (June 7, 2025):

• Updated project dependency to https://github.com/matnoel/meshio.git
• Fixed issue #9: add vizir output format
• Fixed issue #10: format the code with black
• Fixed bug in gauss quadrature for prisms
• Fixed issue #11: add continuous integration with github-actions
• Fixed issue #14: test types with mypy.
• Added new badges in the readme file.

1.4.0 (April 24, 2025):

• Fixed issues #6 and #7.
• Organized the tests/ directory.
• Updated hyperbolic solvers (hht, newmark, midpoint).
• Created a linear algebra module for the Trace, Det, Inv, TensorProd, Transpose, and Norm functions.
• Updated the MeshIO interface. Removed unnecessary node reordering, which is now handled by the https://github.com/matnoel/meshio fork.
• Replaced simu.Get_directions() with simu.Get_unknowns().
• Clarified the groupElem.Get_F_e_pg() function.
• Created simu functions to access Neumann boundary condition values.

1.3.4 (March 28, 2025):

• Moved Display._Init_obj() to _simu._Init_obj().
• Updated the Display.Plot_Result() and PyVista.Plot() functions.
• Updated the Modal1.py and Modal2.py examples.
• Clarified the _GroupElem.Get_F_e_pg() and _GroupElem.Get_invF_e_pg() functions.

1.3.3 (March 22, 2025):

• Created the MeshIO interface.
• Updated the Geoms module.
• Created the params check functions.

1.3.2 (March 16, 2025):

• Updated pyproject.toml (name = "easyfea") to comply with PyPI distribution format specifications.
• Enhanced Gmsh_Interface to support linked surface creation by adding pointTags to the addSurfaceFilling function in Gmsh.

1.3.1 (February 28, 2025):

• Updated Folder functions (New_File -> Join(mkdir=True), Get_Path() -> Dir())
• Removed colors in Display.Plot_Tags()
• Updated the method for setting up a tag in a mesh (_Set_Nodes_Tag and _Set_Elements_Tag).
• Removed the old trick to generate the mesh with gmsh recombine
• Updated Gmsh_Interface tests (test_mesh_isOrganised).
• Enhanced examples.

1.3.0 (February 24, 2025):

• Implemented new element types: QUAD9, SEG5, TRI15, HEXA27, PRISM18.
• Enhanced Gmsh_Interface for QUAD and HEXA elements.
• Standardized shape functions.
• Updated Paraview_Interface and PyVista_Interface.
• Updated Gauss points quadrature.
• Migrated from unittest to pytest.
• Enhanced examples.

1.2.7 (February 7, 2025):

• Enhanced Gmsh_Interface.
• Finite element shape functions were renamed to improve code readability.
• NEW YEAR.

1.2.6 (November 7, 2024):

• Enhanced the Digital Image Correlation (DIC) analysis module.
• Enhanced examples.
• Updated docstrings.
• Updated Display functions.

1.2.5 (September 27, 2024):

• Updated phase field solver.

1.2.4 (September 22, 2024):

• Updated docstrings.
• Updated Display functions.
• Updated PyVista_Interface functions.
• Added _Elas.Get_sqrt_C_S() function.
• Updated He split for heterogeneous material properties.
• Added Save_pickle() and Load_pickle() functions.
• Updated Gmsh_Interface for cracks.
• Updated Folder functions.

1.2.3 (September 11, 2024):

• Ensures compatibility with python 3.9 and 3.10.

1.2.2 (September 10, 2024):

• Updated docstrings.
• Updated simulations/_phasefield.py solver.
• Updated Bc Config.
• Updated tests.
• Updated _Additional_Points().
• Updated Mesh_Beams().

1.2.1 (August 17, 2024):

• Updated docstrings.

1.2.0 (August 14, 2024):

• Added the resetAll option in Set_Iter() to simplify the update process after iteration activation.
• Enhanced clarity in phase field functions, including both simulation and material aspects.
• Improved display options for geometric objects.
• Improved display functions.
• Provided clearer functionality in mesh and group element.
• Updated the interface with Gmsh.
• Improved phasefield examples.
• Enhanced the Digital Image Correlation (DIC) analysis module.

1.1.0 (June 29, 2024):

• Updated gmsh interface functions.
• Added controls when calling certain functions.
• Updated geometric objects to modify parameters after creation.
• Added a banner to the project.
• Added CT.py damage simulation.

1.0.3 (May 16, 2024):

• Minor adjustments to README.md

1.0.2 (May 14, 2024):

• Minor adjustments to object printing.
• Reorganization of save functions in the simulation recording and loading process.
• Modification of the PETSc interface for the new version.
• Implemented minor refinements in Solvers.py to ensure correct canonical values of matrix A in Ax=b equations, thus avoiding potential bugs when using PETSc or pypardiso.
• Renamed functions in fem/_gauss.py to improve clarity and consistency.
• Updated function names in Display.py to improve readability.
• Updated copyright information to reflect the latest changes.
• Added a contribution guide to facilitate community participation and collaboration.
• Creation of a citation file.

1.0.1 (April 13, 2024):

• Update library dependencies.

1.0.0 (April 13, 2024):

• First version.