fm_fem: Compute finite element matrices

In fmesher: Triangle Meshes and Related Geometry Tools

Compute finite element matrices

Description

Compute finite element mass and structure matrices

Usage

fm_fem(mesh, order = 2, ...)

## S3 method for class 'fm_mesh_1d'
fm_fem(mesh, order = 2, ...)

## S3 method for class 'fm_mesh_2d'
fm_fem(mesh, order = 2, aniso = NULL, ...)

## S3 method for class 'fm_tensor'
fm_fem(mesh, order = 2, ...)

## S3 method for class 'fm_collect'
fm_fem(mesh, order = 2, ...)

## S3 method for class 'fm_mesh_3d'
fm_fem(mesh, order = 2, ...)

Arguments

mesh	fm_mesh_1d(), fm_mesh_2d(), or other supported mesh class object
order	integer; the maximum operator order
...	Currently unused
aniso	If non-NULL, a list(gamma, v). Calculates anisotropic structure matrices (in addition to the regular) for \gamma and v for an anisotropic operator \nabla\cdot H \nabla, where H=\gamma I + v v^\top. Currently (2023-08-05) the fields need to be given per vertex.

Value

fm_fem.fm_mesh_1d: A list with elements c0, c1, cc, g1, g2, etc. When mesh$degree == 2, also g01, g02, and g12, and cc is the same as c1, usually the natural choice for precision matrix construction. When mesh$degree < 2, cc is the same as c0.

fm_fem.fm_mesh_2d: A list with elements c0, c1, cc, g1, va, ta, and more if order > 1. When aniso is non-NULL, also g1aniso matrices, etc. The cc matrix is meant to be used for precision materix constructions, and is currently equal to c0.

fm_fem.fm_tensor: A list with elements cc, g1, g2.

fm_fem.fm_collect: A list with elements c0, c1, g1, g2, etc, and cc (cc for every model returning cc from fm_fem(), and c0 when cc is not available). If the base type for the collection provides va and ta values, those are also returned.

fm_fem.fm_mesh_3d: A list with elements c0, c1, cc, g1, g2, va, ta, and more if order > 2.

Examples

names(fm_fem(fm_mesh_1d(1:4), order = 3))
names(fm_fem(fmexample$mesh, order = 3))

fmesher documentation built on June 24, 2026, 1:06 a.m.