topology¶
The topology module defines the topology objects, notably the
StructuredTopology
. Maintaining strict separation of topological and
geometrical information, the topology represents a set of elements and their
interconnectivity, boundaries, refinements, subtopologies etc, but not their
positioning in physical space. The dimension of the topology represents the
dimension of its elements, not that of the the space they are embedded in.
The primary role of topologies is to form a domain for nutils.function
objects, like the geometry function and function bases for analysis, as well as
provide tools for their construction. It also offers methods for integration and
sampling, thus providing a high level interface to operations otherwise written
out in element loops. For lower level operations topologies can be used as
nutils.element
iterators.

class
nutils.topology.
Topology
(references, transforms, opposites)¶ Bases:
nutils.types.Singleton
topology base class

__str__
(self)¶ string representation

basis
(self, name, *args, **kwargs)¶ Create a basis.

sample
(self, ischeme, degree)¶ Create sample.

integrate_elementwise
(self, funcs, *, asfunction=False, **kwargs)¶ elementwise integration

integrate
(self, funcs, ischeme='gauss', degree=None, edit=None, *, arguments=None, title='integrate')¶ integrate functions

integral
(self, func, ischeme='gauss', degree=None, edit=None)¶

projection
(self, fun, onto, geometry, **kwargs)¶ project and return as function

project
(self, fun, onto, geometry, ischeme='gauss', degree=None, droptol=1e12, exact_boundaries=False, constrain=None, verify=None, ptype='lsqr', edit=None, *, arguments=None, **solverargs)¶ L2 projection of function onto function space

refined_by
(self, refine)¶ create refined space by refining dofs in existing one

refine
(self, n)¶ refine entire topology n times

trim
(self, levelset, maxrefine, ndivisions=8, name='trimmed', leveltopo=None, *, arguments=None)¶ trim element along levelset

subset
(self, topo, newboundary=None, strict=False)¶ intersection

locate
(self, geom, coords, *, ischeme='vertex', scale=1, tol=None, eps=0, maxiter=100, arguments=None)¶ Create a sample based on physical coordinates.
In a finite element application, functions are commonly evaluated in points that are defined on the topology. The reverse, finding a point on the topology based on a function value, is often a nonlinear process and as such involves Newton iterations. The
locate
function facilitates this search process and produces anutils.sample.Sample
instance that can be used for the subsequent evaluation of any function in the given physical points.Example:
>>> from . import mesh >>> domain, geom = mesh.unitsquare(nelems=3, etype='mixed') >>> sample = domain.locate(geom, [[.9, .4]]) >>> sample.eval(geom).tolist() [[0.9, 0.4]]
Locate has a long list of arguments that can be used to steer the nonlinear search process, but the default values should be fine for reasonably standard situations.
 Parameters
geom (1dimensional
nutils.function.Array
) – Geometry function of lengthndims
.coords (2dimensional
float
array) – Array of coordinates withndims
columns.tol (
float
) – Maximum allowed distance between original and located coordinate.ischeme (
str
(default: “vertex”)) – Sample points used to determine bounding boxes.scale (
float
(default: 1)) – Bounding box amplification factor, useful when element shapes are distorted. Setting this to >1 can increase computational effort but is otherwise harmless.eps (
float
(default: 0)) – Epsilon radius around element within which a point is considered to be inside.maxiter (
int
(default: 100)) – Maximum allowed number of Newton iterations.arguments (
dict
(default: None)) – Arguments for function evaluation.
 Returns
located
 Return type

basis_discont
(self, degree)¶ discontinuous shape functions

basis_lagrange
(self, degree)¶ lagrange shape functions

basis_bernstein
(self, degree)¶ bernstein shape functions

basis_std
(self, degree)¶ bernstein shape functions


class
nutils.topology.
WithGroupsTopology
(basetopo, vgroups={}, bgroups={}, igroups={}, pgroups={})¶ Bases:
nutils.topology.Topology
item topology

class
nutils.topology.
OppositeTopology
(basetopo)¶ Bases:
nutils.topology.Topology
opposite topology

class
nutils.topology.
EmptyTopology
(ndims)¶ Bases:
nutils.topology.Topology
empty topology

class
nutils.topology.
Point
(trans, opposite=None)¶ Bases:
nutils.topology.Topology
point

class
nutils.topology.
StructuredTopology
(root, axes, nrefine=0, bnames='left', 'right', 'bottom', 'top', 'front', 'back')¶ Bases:
nutils.topology.Topology
structured topology

__init__
(self, root, axes, nrefine=0, bnames='left', 'right', 'bottom', 'top', 'front', 'back')¶ constructor

boundary
¶

interfaces
¶

basis_spline
(self, degree, removedofs=None, knotvalues=None, knotmultiplicities=None, continuity= 1, periodic=None)¶ spline basis

property
refined
¶ refine nonuniformly

__str__
(self)¶ string representation


class
nutils.topology.
ConnectedTopology
(references, transforms, opposites, connectivity)¶ Bases:
nutils.topology.Topology
unstructured topology with connectivity

class
nutils.topology.
SimplexTopology
(simplices, transforms, opposites)¶ Bases:
nutils.topology.Topology
simpex topology

basis_bubble
(self)¶ bubble from vertices


class
nutils.topology.
UnionTopology
(topos, names=())¶ Bases:
nutils.topology.Topology
grouped topology

class
nutils.topology.
DisjointUnionTopology
(topos, names=())¶ Bases:
nutils.topology.Topology
grouped topology

class
nutils.topology.
SubsetTopology
(basetopo, refs, newboundary=None)¶ Bases:
nutils.topology.Topology
trimmed

class
nutils.topology.
RefinedTopology
(basetopo)¶ Bases:
nutils.topology.Topology
refinement

class
nutils.topology.
HierarchicalTopology
(basetopo, indices_per_level)¶ Bases:
nutils.topology.Topology
collection of nested topology elments

__init__
(self, basetopo, indices_per_level)¶ constructor

boundary
¶ boundary elements

interfaces
¶

basis
(self, name, *args, truncation_tolerance=1e15, **kwargs)¶ Create hierarchical basis.
A hierarchical basis is constructed from bases on different levels of uniform refinement. Two different types of hierarchical bases are supported:
1. Classical – Starting from the set of all basis functions originating from all levels of uniform refinement, only those basis functions are selected for which at least one supporting element is part of the hierarchical topology.
2. Truncated – Like classical, but with basis functions modified such that the area of support is reduced. An additional effect of this procedure is that it restores partition of unity. The spanned function space remains unchanged.
Truncation is based on linear combinations of basis functions, where fine level basis functions are used to reduce the support of coarser level basis functions. See Giannelli et al. 2012 for more information on truncated hierarchical refinement.
 Parameters
name (
str
) – Type of basis function as provided by the base topology, with prefixh
(hstd
,hspline
) for a classical hierarchical basis and prefixth
(thstd
,thspline
) for a truncated hierarchical basis.truncation_tolerance (
float
(default 1e15)) – In order to benefit from the extra sparsity resulting from truncation, vanishing polynomials need to be actively identified and removed from the basis. Thetrunctation_tolerance
offers control over this threshold.
 Returns
basis
 Return type


class
nutils.topology.
ProductTopology
(topo1, topo2)¶ Bases:
nutils.topology.Topology
product topology

class
nutils.topology.
RevolutionTopology
¶ Bases:
nutils.topology.Topology
topology consisting of a single revolution element

class
nutils.topology.
MultipatchTopology
(patches)¶ Bases:
nutils.topology.Topology
multipatch topology

static
build_boundarydata
(connectivity)¶ build boundary data based on connectivity

__init__
(self, patches)¶ constructor

basis_spline
(self, degree, patchcontinuous=True, knotvalues=None, knotmultiplicities=None, *, continuity= 1)¶ spline from vertices
Create a spline basis with degree
degree
per patch. Ifpatchcontinuous`
is true the basis is $C^0$continuous at patch interfaces.

basis_patch
(self)¶ degree zero patchwise discontinuous basis

boundary
¶

interfaces
¶ Return a topology with all element interfaces. The patch interfaces are accessible via the group
'interpatch'
and the interfaces inside a patch via'intrapatch'
.

refined
¶ refine

static