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MFEM + PyMFEM (FEM library)

This repository provides Python binding for MFEM. MFEM is a high performance parallel finite element method (FEM) library (http://mfem.org/).

Installer (setup.py) builds both MFEM and binding together. By default, "pip install mfem" downloads and builds the serial version of MFEM and PyMFEM. Additionally, the installer supports building MFEM with specific options together with other external libraries, including MPI version.

Install

pip install mfem                    # binary install is available only on linux platforms (Py36-39) 
pip install mfem --no-binary mfem   # install serial MFEM + wrapper

Using additional features (MPI, GPU, GPU-Hypre, GSLIB, SuiteSparse)

The setup script accept various options. TO use it, please download the package and run the script manually. For example, this below download and build parallel version of MFEM library (linked with Metis and Hypre) and install under /mfem. See also, docs/install.txt

$ pip3 download mfem
(expand tar.gz file and move to the downloaded directory)
$ python setup.py install --with-parallel # it download and build metis/hypre/mfem

Choosing compiler

$ python setup.py install --with-parallel --CC=icc --CXX=icpc --MPICC=mpiicc --MPICXX=mpiicpc

For other configurations, see docs/install.txt or help

$ python setup.py install --help

Install from github master

git clone https://github.com/mfem/PyMFEM.git
cd PyMFEM
python setup.py install --mfem-branch=master  # build both MFEM and PyMFEM
  
cd test
python test_examples.py -serial

Usage

Here is an example to solve div(grad(f)) = 1 in a square and to plot the result with matplotlib (modified from ex1.cpp). Use the badge above to open this in Binder.

import mfem.ser as mfem

# create sample mesh for square shape
mesh = mfem.Mesh(10, 10, "TRIANGLE")

# create finite element function space
fec = mfem.H1_FECollection(1, mesh.Dimension())   # H1 order=1
fespace = mfem.FiniteElementSpace(mesh, fec)      

# 
ess_tdof_list = mfem.intArray()
ess_bdr = mfem.intArray([1]*mesh.bdr_attributes.Size())
fespace.GetEssentialTrueDofs(ess_bdr, ess_tdof_list)

# constant coefficient 
one = mfem.ConstantCoefficient(1.0)

# define Bilinear and Linear operator
a = mfem.BilinearForm(fespace)
a.AddDomainIntegrator(mfem.DiffusionIntegrator(one))
a.Assemble()
b = mfem.LinearForm(fespace)
b.AddDomainIntegrator(mfem.DomainLFIntegrator(one))
b.Assemble()

# create gridfunction, which is where the solution vector is stored
x = mfem.GridFunction(fespace);
x.Assign(0.0)

# form linear equation (AX=B)
A = mfem.OperatorPtr()
B = mfem.Vector()
X = mfem.Vector()
a.FormLinearSystem(ess_tdof_list, x, b, A, X, B);
print("Size of linear system: " + str(A.Height()))

# solve it using PCG solver and store the solution to x
AA = mfem.OperatorHandle2SparseMatrix(A)
M = mfem.GSSmoother(AA)
mfem.PCG(AA, M, B, X, 1, 200, 1e-12, 0.0)
a.RecoverFEMSolution(X, b, x)

# extract vertices and solution as numpy array
verts = mesh.GetVertexArray()
sol = x.GetDataArray()

# plot solution using Matplotlib

import matplotlib.pyplot as plt
import matplotlib.tri as tri

triang = tri.Triangulation(verts[:,0], verts[:,1])

fig1, ax1 = plt.subplots()
ax1.set_aspect('equal')
tpc = ax1.tripcolor(triang, sol, shading='gouraud')
fig1.colorbar(tpc)
plt.show()

License

PyMFEM is licensed under BSD-3. Please refer the developers' web sites for the external libraries