CHANGELOG.md

Changelog

Note: Palace is under active initial development, pre-v1.0. Functionality and interfaces may change rapidly as development progresses.

The format of this changelog is based on Keep a Changelog, and this project adheres to Semantic Versioning.

In progress

New Features

• Expanded JSON schema validation to cover required fields, mutual exclusion constraints (e.g., PEC/Ground, PMC/ZeroCharge), array type validation, and numeric bounds. Many runtime checks are now caught earlier at configuration parsing time with clearer error messages PR 635.

Bug Fixes

• Improved IO performance for simulations with Adaptive Mesh Refinement. Now, files from previous iterations are moved instead of being copied. The latest output is always available at the top level of the output directory (as symlinks to the latest iterationXX folder). PR 673
• Fixed port excitation parsing to correctly handle signed integer values PR 635.

[0.16.0] - 2026-03-05

New Features

• Added PALACE_BUILD_WITH_SANITIZERS CMake option and asan Spack variant for AddressSanitizer and UndefinedBehaviorSanitizer support. PR 642
• Added reporting for memory used by Palace. Peak values are also stored in postpro/palace.json. PR 629
• Added JSON schema validation for configuration files at runtime, with embedded schemas and detailed error messages including valid enum options PR 613.
• Added support for electric current dipole source excitations. Current dipoles can be configured as an array in config["Domains"]["CurrentDipole"] with specifications for "Index", "Moment", "Center", and "Direction". Consult the documentation for additional information. PR 556.
• Added an option to specify the number of AMS iterations in config["Solver"]["Linear"]["AMSMaxIts"], with the default value changed from 1 to the solution order, and changed some of the AMS options. PR 625.
• Added support for circuit synthesis from the ROM in adaptive driven simulations (config["Solver"]["Driven"]["AdaptiveCircuitSynthesis"]). Modifies ROM to add LumpedPort fields to make circuit. Prints out the projected matrices of the driven problem as well as the basis orthogonalization matrix. Extended tests on aspects related to ROM and LumpedPortOp. PR 326.
• Upgraded internal orthogonalization routines to optionally allow taking non-identity weights in inner product. Part of PR 326.

Bug Fixes

• Fixed a bug in the computation of the waveport maximum propagation constant in parallel simulations PR 580.
• Fixed a bug where BdrFieldCoefficient::Eval used a comma operator instead of addition when computing the average of field values on interior boundaries, causing incorrect results for interior trace postprocessing. PR 621.
• Fixed a bug in complex diagonal operator multiplication where the imaginary part used an incorrect term in AddMult and AddMultHermitianTranspose. PR 633.

Interface Changes

• config["Boundaries"]["Terminal"] must now be used for electrostatic simulations to compute capacitance matrices, and config["Boundaries"]["SurfaceCurrent"] for magnetostatic simulations to compute inductance matrices. Previously, terminals and surface current sources could also be specified under "LumpedPort". PR 624.
• config["Solver"]["Eigenmode"]["Target"] is now always required for eigenmode simulations. Previously, it could be omitted if a "Driven" section was also present. PR 624.

[0.15.0] - 2025-12-2

New Features

• Added support for nonlinear eigenvalue problems arising from frequency-dependent boundary conditions. Two nonlinear eigensolvers are now available and can be specified by setting the config["Solver"]["Eigenmode"]["NonlinearType"] option to "Hybrid" (default) or "SLP". The nonlinear eigensolver will automatically be used if frequency-dependent boundary conditions are used. PR 467.
• Added support for extraction of electric fields in the radiative zone. Consult the documentation for additional information. PR 449.
• Added support for more granular tests and for computing the testing coverage. Consult the documentation for additional information. PR 398, PR 480.
• Added option to export field solutions as MFEM grid functions to visualize with GLVis. Output formats can be specified in config["Problem"]["OutputFormats"]. PR 518.
• Added an option to drop small entries (below machine epsilon) from the matrix used in the sparse direct solver. This can be specified with config["Solver"]["Linear"]["DropSmallEntries"]. PR 476.

Interface Changes

• config["Boundaries"]["Periodic"] is now a dictionary where all periodic boundary pairs, built into the mesh file or not, should be specified in config["Boundaries"]["Periodic"]["BoundaryPairs"] and a single global Floquet wave vector can be specified in config["Boundaries"]["Periodic"]["FloquetWaveVector"]. PR 471.
• Changed Paraview and GLVis output fields from nondimensional to SI units PR 532.
• The name of the unit test executable is now palace-unit-tests (instead of unit-tests) PR 549.

Bug Fixes

• Changed wave port eigenproblem shift and sorting to fix an issue with the mode ordering. The first mode now has the largest propagation constant, closest to the TEM limit, and subsequent modes are ordered by decreasing propagation constant. PR 448.
• Fixed an issue where Gmsh meshes with built-in periodicity (specified in the mesh file) were failing. PR 471.
• Fixed bug where a mesh from a previous nonconformal adaptation could not be loaded to use in a non-amr simulation. PR 497.
• Fixed bug where "CrackInternalBoundaryElements" would result in incorrect results for some lumped port boundary conditions. PR 505.
• Changed the sign of the Floquet phase factor from $\exp(+ik\cdot x)$ to $\exp(-ik\cdot x)$. PR 510 and PR 526.
• Update EM constants to CODATA Recommended Values of the Fundamental Physical Constants 2022 PR 525.
• Scaled Rs/Ls/Cs of impedance boundary conditions affected by mesh cracking, fixing bug where "CrackInternalBoundaryElements" would lead to incorrect results. PR 544.
• Fixed Paraview/MFEM output for transient simulations. PR 561.
• Fixed units of energy. Results were incorrectly reported in joules, while the correct unit was nanojoules. Results are now correctly in joules. PR 541.
• Fixed a bug in transient solver implicit formulation affecting the magnetic flux density fields computed with "GeneralizedAlpha" or "RungeKutta" transient solver types (config["Solver"]["Transient"]["Type"]) PR 568.

Build system

• When building on a machine with a GPU, CMAKE_CUDA_ARCHITECTURES has now a default value that is automatically determined to be the consistent with the GPU (when no GPU is detected, CMAKE_CUDA_ARCHITECTURES is set to 70). PR 530.
• The spack Palace build now supports compilation of unit tests with Spack tests. PR 549.
• MFEM is no longer unconditionally compiled alongside of Palace and can now be built separately. This is used in the Palace spack build, which now explicitly depends on MFEM. PR 550.

[0.14.0] - 2025-08-20

• Added --version command line flag for displaying Palace version information.
• Fixed a small regression bug for boundary postprocessing when specifying "Side": "LargerRefractiveIndex", introduced as part of v0.13.0.
• Added an improvement to numeric wave ports to avoid targeting evanescent modes at higher operating frequencies. Also finite conductivity boundaries (config["Boundaries"]["Conductivity"]) are automatically marked as PEC for the wave port mode solve (previously these were marked as PMC unless specified under "WavePortPEC").
• Fixed a bug in divergence-free projection for problems without essential or mixed boundary conditions.
• Added "MakeSimplex" and "MakeHexahedral" mesh options to convert an input mesh to all tetrahedra or all hexahedra. Also adds "SerialUniformLevels" option to config["Model"]["Refinement"] for testing or debugging.
• Added config["Model"]["CrackInternalBoundaryElements"] which will separate or "crack" the mesh along all internal boundaries. This improves the performance of error estimation and AMR as the recovered smooth fields do not enforce additional erroneous continuity at internal boundaries. This will change the default behaviour in the case of internal impedance boundary conditions, and can be disabled by setting this option to false.
• Added support for exact periodic boundary conditions, these can be specified as part of the mesh file (where supported by the format) or by specification of "DonorAttributes" and "ReceiverAttributes" in config["Boundaries"]["Periodic"] which will attempt to match the mesh on the boundaries specified by the donor and receiver attributes. This is only possible the mesh on the donor and receiver match exactly, non-matching meshes are not supported.
• Exposed configuration linear solver and eigen solver options for the wave port subproblem. These can now be specified as part of the config["Boundaries"]["WavePort"] configuration. The defaults align with the previously hardcoded values.
• Nonconformal adaptation is now supported for WavePort boundary conditions. This was achieved through a patch applied to MFEM to support mfem::ParSubMesh on external nonconformal surface subdomains.
• Added adaptive time-stepping capability for transient simulations. The new ODE integrators rely on the SUNDIALS library and can be specified by setting the config["Solver"]["Transient"]["Type"] option to "CVODE" or "ARKODE".
• Added an option to use the complex-valued system matrix for the coarse level solve (sparse direct solve) instead of the real-valued approximation. This can be specified with config["Solver"]["Linear"]["ComplexCoarseSolve"].
• Fix bug in London equation implementation where a curl-curl term was added to the stiffness operator instead of a mass term.
• Added support for Floquet periodic boundary conditions with phase-delay constraints. The Floquet wave vector can be specified along with periodic boundaries in the config["Boundaries"]["Periodic"] configuration.
• Fixed bug where the default config["Model"]["CrackDisplacementFactor"] would cause lumped port discovery to fail by reducing default from 1e-3 to 1e-12.
• Fixed bug in Nastran mesh reader where carriage returns (\r) in the mesh file could cause a failure to read the mesh.
• Changed post-processing, so that appropriate measurements are always written to disk as CSV files. This is a breaking change, since users are now required to specify a valid output folder in config["Problem"]["Output"]. Previously an empty string "" would suppress file printing. ParaView printing is still controlled and suppressed by the "Save" or "SaveStep" options in the config["Solver"][...].
• Changed measurement and printing during post-processing substantially. This change is not user-facing, but will enable future multi-excitation support. All measurements are now performed as part of the PostOperator class, which is templated on solver type. The public interface of the PostOperator has been simplified: measurements can no longer be called individually, but are grouped in a MeasurePrintAll function. The actual printing of measurements has moved out of individual solvers and is orchestrated by the PostOperatorCSV class. Other helper classes include a small Table class (for data storage and formatting) and a light wrapper TableWithCSVFile (with file interaction).
• Changed unit conversion interface: this was moved out of IOData into a separate Units class.
• Changed csv output to print more digits.
• Changed boundary indexing to enforce that the value of Index is unique between LumpedPort, WavePort, SurfaceCurrent and Terminal. This is a breaking change — e.g. currently a lumped port and a wave port could share an index.
• Added multi-excitation support. Excitation in LumpedPort and WavePort boundary conditions can now be specified either as bools or excitation integers. Allow driven simulations to have multiple excitations indices in same configuration file to be simulated consecutively during the same Palace run. The measurement output of multiple excitations is printed to the same csv files with distinguish columns being post-indexed by the excitation index.
• Changed RomOperator to split out rational interpolation component into the separate MinimalRationalInterpolation class to support multiple excitations. The MRI is unique to each excitation, but the PROM is shared between excitations.
• Added PortExcitations to manage excitation pattern and print it to json metadata.
• Update spack configuration to address 0.12 API breakage between libxsmm and libCEED.
• Support spack vended libCEED and GSLIB builds.
• Fix bug where MakeSimplex would fail for higher order meshes.
• Fix bug in STRUMPACK build where dependency SCALAPACK library install directory could change based on build environment.
• Introduce "Samples" mechanism for driven simulation, which allows for specifying a range of sample frequencies by combining "Linear", "Log" and "Point" specifications. These are joined together effectively allowing for variable resolution sampling (for examples a coarse sampling supported by a fine sampling in a subset region). This is in addition to the prior existing "MinFreq", "MaxFreq", "FreqStep" interface which is now implicitly converted to a "Linear" sample scheme internally.
• Introduce "Save" keyword for "Driven" simulation type, which will save specific frequency choices as opposed to the existing (and maintained "SaveStep" based on a regular sampling). Only frequencies contained within the set of "Samples" are supported, as no interpolation is performed.
• Fix bugs in post processing where E_cap, E_ind, and mode_port_kappa and other dependent quantities were not dimensionalized correctly.
• Refactor PostOperator usage of Measurement to be entirely non-dimensional, until PostOperatorCSV which dimensionalizes all measurements before writing to file. Reduces the risk of mixed unit bugs throughout PostOperator.
• Fix bug in using "MakeSimplex" which would cause undefined behaviour for higher order meshes.
• Fix bug when combining OpenMP and GPU builds in reduction operations over Vector.
• Fix race condition that would affect OpenMP parallelism with periodic boundaries (exact and Floquet).
• Fix race condition in mfem::DenseTensor::operator() with OpenMP, due to class member variable access.
• Fix race condition in DofToQuad methods within mfem.
• Normalize eigenmodes so their mean phase is a positive real number.
• Added scnlib as a dependency to Palace.
• Added parsing ability of existing csv files into the Table class. Fix "Restart" behaviour with the multi-excitation feature of driven solver.

[0.13.0] - 2024-05-20

• Changed default value of config["Solver"]["PartialAssemblyOrder"] in order to activate operator partial assembly by default for all operators in all simulation types.
• Changed the normalization of computed eigenmodes for consistency across different domain decompositions. Eigenvectors are now normalized with respect to the mass matrix for unit domain electric field energy.
• Added documentation for various timer categories and improved timing breakdown of various sections of a simulation.
• Changed mesh files for the cavity and CPW examples, including prism, hexahedral, and tetrahedral meshes for the cylindrical cavity and correcting the wave port dimensions for the coplanar wave guide.
• Fixed a few bugs and issues in the implementation of numeric wave ports for driven simulations.
• Added GPU support for Palace via its dependencies, and added the config["Solver"]["Device"] and config["Solver"]["Backend"] options for runtime configuration of the MFEM device ("CPU" or "GPU") and libCEED backend, with suitable defaults for users.
• Added a new section to the documentation on Parallelism and GPU support.
• Removed use of mfem::SparseMatrix and replaced with HYPRE's hypre_CSRMatrix when needed for full assembly, wrapped as palace::hypre::HypreCSRMatrix.
• Added "Active" configuration file parameter for lumped and wave port boundaries to disable the associated boundary condition and only use the surface for postprocessing.
• Changed the smooth flux space for the electrostatic error estimator to fix performance on problems with material interfaces.
• Fixed error estimation bug affecting time-dependent simulation types (driven, transient, eigenmode) where the recovery of the electric flux density also needs to be taken into account in addition to the magnetic field.
• Fixed a bug related to mesh cleaning for unspecified domains and mesh partitioning.
• Change computation of domain energy postprocessing for electrostatic and magnetostatic simulation types in order to improve performance.
• Fixed a bug when computing the energy associated with lumped elements with more than one nonzero R, L, or C. This also affects the inductive EPR for lumped inductors with and associated parallel capacitance.
• Fixed a bug for coaxial lumped ports which led to incorrect extraction of the geometric parameters, especially when coarsely-meshed or non-axis-aligned.
• Added boundary postprocessing functionality for surface flux including electric, magnetic, and power given by the Poynting vector. This results in some breaking changes to the configuration file interface, see config["Boundaries"]["Postprocessing"]["SurfaceFlux"] and config["Boundaries"]["Postprocessing"]["Dielectric"]. In addition, related configuration file keyword changes to for consistency were made to config["Domains"]["Postprocessing"]["Probe"] and config["Model"]["Refinement"]["Boxes"].
• Fixed a bug in MFEM for nonconformal AMR meshes with internal boundaries affecting non-homogeneous Dirichlet boundary conditions for electrostatic simulations (see #236).

[0.12.0] - 2023-12-21

• Added support for operator partial assembly for high-order finite element spaces based on libCEED for mixed and non-tensor product element meshes. This option is disabled by default, but can be activated using config["Solver"]["PartialAssemblyOrder"] set to some number less than or equal to "Order".
• Added flux-based error estimation, reported in error-estimate.csv. This computes the difference between the numerical gradient (electrostatics) or curl (otherwise) of the solution, and a smoother approximation obtained through a global mass matrix inversion. The results are reported in error-estimates.csv within the "Output" folder.
• Added Adaptive Mesh Refinement (AMR), specified in the config["Model"]["Refinement"], for all problem types aside from transient. To enable AMR, a user must specify "MaxIts", while all other options have reasonable defaults. Nonconformal (all mesh types) and conformal (simplex meshes) refinement are supported.
• Added support for non-axis-aligned lumped ports and current sources. Key words "X", "Y", "Z" and "R", with optional prefix "+" or "-" still work, but now directions can be specified as vectors with 3 components. Users will be warned, and ultimately errored, if the specified directions do not agree with axis directions discovered from the geometry.
• Added output of lumped port voltage and current for eigenmode simulations.
• Added dimensionalized output for energies, voltages, currents, and field values based on a choice of the characteristic magnetic field strength used for nondimensionalization.
• Added output of electric and magnetic field energies and participation ratios in regions of the domain, specified with config["Domains"]["Postprocessing"]["Energy"] and written to domain-E.csv. This replaces config["Domains"]["Postprocessing"]["Dielectric"] and domain-Q.csv.
• Added improved Timer and BlockTimer classes with more timing categories for reporting simulation runtime.
• Changed implementation of complex-valued linear algebra to use new ComplexVector and ComplexOperator types, which are based on the underlying mfem::Vector and mfem::Operator classes, instead of PETSc. PETSc is now fully optional and only required when SLEPc eigenvalue solver support is requested. Krylov solvers for real- and complex-valued linear systems are implemented via the built-in IterativeSolver classes.
• Changed implementation of PROMs for adaptive fast frequency sweep to use the Eigen library for sequential dense linear algebra.
• Changed implementation of numeric wave ports to use MFEM's SubMesh functionality. As of #3379 in MFEM, this has full ND and RT basis support. For now, support for nonconforming mesh boundaries is limited.
• Added build dependencies on libCEED, including LIBXSMM and MAGMA to support CPU- and GPU-based operator partial assembly.
• Added unit test framework for all integrators based on Catch2, which also includes some automated benchmarking capabilities for operator assembly and application.
• Added improved OpenMP support in palace wrapper script and CI tests.
• Added Apptainer/Singularity container build definition for Palace.
• Fixed bugs related to thread-safety for OpenMP builds and parallel tetrahedral meshes in the upstream MFEM library.

[0.11.2] - 2023-07-14

• Fixed a regression bug affecting meshes which have domain elements which are not assigned material properties in the configuration file.
• Changed layout and names of palace/ source directory for better organization.
• Added many updates to build system: Removed use of Git submodules to download dependencies relying instead directly on CMake's ExternalProject, patch GSLIB dependency for shared library builds, add CI tests with ARPACK-NG instead of SLEPc, update all dependency versions including MFEM to incorporate bug fixes and improvements. This affects the Spack package recipe, so a new recipe is distributed as part of Palace in in spack/ which will keep compatibility with main while changes are upstreamed to the built-in Spack repository.
• Added a basic Makefile with some useful targets for development.

[0.11.1] - 2023-05-03

• Fixed a bug for interface dielectric loss postprocessing including when using --dry-run.
• Fixed a regression bug affecting second-order absorbing boundary conditions.
• Fixed a bug when the number of processors was large enough that some subdomains own no true dofs.
• Fixed memory bug in destruction of SuperLU solver.
• Fixed some typos in the documentation.
• Fixed a bug in the cavity convergence study example for the coarsest hexahedral mesh case, as well as some other minor Julia fixes in the examples/ and scripts/ directories.
• Added updates to superbuild including better ARPACK support, though still experimental compared to SLEPc.
• Added updated submodules for superbuild.

[0.11.0] - 2023-01-26

• Initial public release on GitHub.
• Added support for anisotropic materials through the use of "MaterialAxes" under "Materials". These material axes allow for specifying symmetric material property tensors through a sum of weighted outer products of normal vectors. This can be used in conjunction with scalar material properties or multiple different anisotropic properties, though all properties are required to use the same set of basis vectors. Demonstration given for the coplanar waveguide example which now utilizes a sapphire substrate.
• Added to default postprocessing outputs: Bulk and interface dielectric loss writes energy-participation ratios in addition to quality factors associated with lossy regions, IO coupling $\kappa$ in addition to quality factor for eigenmode simulations, lumped element energy for transient simulations similar to eigenmode and frequency domain driven simulations.
• Changed configuration file syntax to simplify support for multielement lumped ports, where each index for a multielement port should now use the "Elements" object to describe the attributes for each port element.
• Changed configuration file keywords to better reflect meaning: config["Boundaries"]["Current"] => config["Boundaries"]["SurfaceCurrent"], and "UseGMG", "UsePCShifted", "MGCycleIts", and "MGSmoothIts" under config["Solver"]["Linear"].
• Changed geometric multigrid implementation to generalize across problem types (added for electrostatics) and use Jacobi-preconditioned Chebyshev smoothing with optional auxiliary space smoothing at each multigrid level as well. The auxiliary space matrices are constructed directly in H1 now to allow for matrix-free/partial-assembly support eventually. Geometric multigrid is turned on by default.
• Added structured simulation metadata output in the form of a JSON file palace.json written to the directory specified by config["Problem"]["Output"].
• Added JSON Schema files for the configuration file format as well as a helper script to check a provided configuration file against the schema.
• Added optional interface to GSLIB library which enables "Probe" functionality to sample the computed electric and magnetic fields at points in space.
• Added preliminary support for builds using Spack. This includes an option in the build system for user-supplied dependencies as an alternative to the superbuild configuration.
• Added updated submodules for superbuild, fixing a bug in SuperLU_DIST solver causing communication hangs for certain numbers of processors.

[0.10.0] - 2022-10-04

• Added interfaces to ARPACK and FEAST eigenvalue solvers.
• Added divergence-free projection for eliminating spurious DC modes for eigenmode solves.
• Added option for visualizing fields on mesh boundaries, output alongside the full 3D solution fields for ParaVeiew visualization.
• Added real and imaginary fields output for complex-valued phasors, and electric and magnetic energy density fields.
• Added convergence study for the cavity example application, and example Julia code for automated mesh generation, running of the solver, and postprocessing.
• Fixed bugs in mesh preprocessing related to precision of nodal coordinates when distributing a serial mesh to each process.
• Added option for "Driven" and "Transient" simulations to accelerate postprocessing by only considering port boundaries.
• Added -dry-run/--dry-run command line option to check configuration file for errors and exit.
• Changed dependency build process to rely less on PETSc build system, no longer give option to build BLAS/LAPACK libraries from source, added detection for OpenBLAS and AMD Optimizing CPU Libraries (AOCL) blis/libflame.
• Fixed issues when compiling with Intel or Clang compilers.
• Added CI test builds to test various build options and added easier default build options in CMake configuration.
• Added clang-format and JuliaFormatter configurations for automated C++, Julia, and Markdown code formatting.

[0.9.0] - 2022-07-11

• Added region-based mesh refinement with box or sphere refinement regions.
• Added new sparse direct solver interfaces to SuperLU_DIST and STRUMPACK libraries, to complement the existing MUMPS interface.
• Changed configuration file keywords for linear solver and preconditioner parameters to make more options available to the user and clarify them.
• Added check that all external boundary surface attributes must have an associated boundary condition specified in the configuration file (adds new "PMC" and "ZeroCharge" boundaries for natural boundary conditions).
• Added advanced configuration options for GMRES/FGMRES/SLEPc eigenvalue solver orthogonalization, making CGS2 (classical GS with iterative refinement) the default.

[0.8.0] - 2022-06-06

• Added new comprehensive example applications and detailed tutorials in the documentation.
• Added CI pipeline for build and regression testing.
• Fixed bugs for shared library builds, which are now the default for dependency builds.
• Added complex lumped port voltage and current output for computing impedance and admittance parameters from frequency domain driven simulations.
• Fixed a bug in mesh parsers for COMSOL and Nastran formats for high-order hexahedra, prism, and pyramid element types.
• Changed adaptive frequency sweep implementation to introduce optimizations which, in particular, speed up driven simulations with wave ports.
• Fixed bug related to domain dielectric postprocessing and surface dielectric loss postprocessing now automatically detects correct side for substrate-air interfaces (always evaluates on vacuum side).

[0.7.0] - 2022-03-25

• Added adaptive fast frequency sweep implementation for frequency domain driven simulations, activated with config["Solver"]["Driven"]["AdaptiveTol"] > 0.0.
• Changed ASCII file postprocessing to write out .csv files instead of generic whitespace delimited .txt for easier parsing.
• Changed field output postprocessing for visualization to save the mesh in the original mesh length units (rather than nondimensionalized ones).
• Added electric and magnetic field energy output to files as function of mode, frequency, time, or solution step, in domain-E.csv.
• Added option to specify circuit R/L/C parameters for lumped port boundaries as an alternative to the surface Rs/Ls/Cs ones.
• Added improved and expanded documentation.
• Added new MFEM features, including support for ND and RT spaces on wedge or prism elements and bug fixes.

[0.6.0] - 2022-02-17

• Changed implementation of boundary conditions and excitations to do a better job separating spatial discretization and algebraic operators. This is also in preparation for future additions of boundary conditions which are not quadratic in the frequency such as wave ports, as well as linear algebra improvements.
• Added a config["Boundaries"]["Current"] configuration file parameter to specify a surface current excitation, and removed the lumped port "Termination" option as it is no longer relevant. Magnetostatics simulations use this "Current" excitation rather than "Port" now.
• Changed lumped port and surface current excitations to now use a unit circuit voltage and circuit current excitation, rather than unit electric field or surface current density.
• Added numeric wave port boundaries for frequency domain driven simulations. To differentiate, lumped port boundaries are now specified using the keyword "LumpedPort" instead of just "Port" in the configuration file.
• Fixed farfield boundaries to account for non-vacuum materials at the boundary and added second-order option for absorbing boundary condition (ABC).
• Added finite conductivity surface impedance boundary condition, with optional thickness correction.
• Added dielectric loss calculation specializations for metal-air, metal-substrate, and substrate-air interfaces in accordance with this paper.
• Changed implementation of frequency domain linear algebra to eliminate the use of PETSc matrix types, relying instead on wrappers of the real and imaginary Hypre matrices making up a complex operator.
• Added geometric multigrid AMS solvers (in two variants) using h- or p-coarsening, which employs either a specialized smoother for Nedelec space coarsening or geometric coarsening for the auxiliary space solves.
• Changed build process to include PETSc as a submodule and configure as part the standard CMake build process.

[0.5.0] - 2021-11-08

• Changed postprocessing implementation which leads to some configuration file changes, namely config["Domains"]["Postprocessing"] and config["Boundaries"]["Postprocessing"].
• Changed some filenames for postprocessed quantities to be more intuitive.
• Added dielectric (bulk and interface) loss calculations for all simulation types. Correctly handles two-sided internal surfaces using "Side" specification.
• Added mutual capacitance matrix extraction to electrostatic solver.
• Added built-in mesh support for COMSOL (.mphbin and .mphtxt) and Nastran (.nas and .bdf) mesh formats.
• Removed Gmsh dependency for mesh format conversion.
• Added some improvements to the default build flags and dependency build options.

[0.4.0] - 2021-09-27

• Added "Capacitance" and "Inductance" options to extract surface charges and fluxes in frequency and time domain simulation types.
• Changed "Transient" solver implementation to use real-valued scalars (user must use a domain electrical conductivity as opposed to a loss tangent for loss modeling), for a roughly 2x performance improvement.
• Added new MFEM features, including upgrades to high-order Nedelec element spaces on tetrahedra which no longer require global dof reordering.
• Changed system matrix assembly to use Hypre P^T A P within MFEM and keep the full dense element matrices when the coefficient is nonzero (skip_zeros = 0 always). The stiffness and mass matrices thus always share the same sparsity pattern now.

[0.3.0] - 2021-09-02

• Added electrostatic solver for capacitance matrix extraction.
• Added "Termination" option for ports to allow for open or short circuiting but still enabling port postprocessing.
• Changed timer to separate out time spent for disk I/O during initialization and postprocessing.
• Added options to job wrappers for new instance types and subnet ID option.
• Added changes from Hypre and MFEM dependencies to include improvements and bug fixes from those libraries.

[0.2.0] - 2021-06-25

• Added a proper changelog for the project.
• Added time domain solver with various excitation options to accompany existing frequency domain driven and eigenmode simulation types.
• Added wrapper scripts in bin/ for launching parallel simulations either interactively or as batch jobs using PBS.
• Changed JSON configuration file keywords for frequency and time intervals.
• Added domain conductivity models for normal and superconducting metals.
• Fixed a bug for coaxial lumped port postprocessing.
• Added visualization of surface currents on domain boundaries to accompany existing $\bm {E}$- and $\bm{B}$-field visualization.
• Changed default length scale for nondimensionalization.
• Changed default filenames for port-related postprocessed quantities.
• Fixed many smaller issues and added various other improvements.

[0.1.0] - 2020-11-03

• Initial development release.