SubDomain

SubDomain(*args, **kwargs)

Base class to define Grid subdomains.

To create a new SubDomain, all one needs to do is overriding :meth:define. This method takes as input a set of Dimensions and produce a mapper

``M : Dimensions -> {d, ('left', N), ('middle', N, M), ('right', N)}``

so that:

* If ``M(d) = d``, then the SubDomain spans the entire Dimension ``d``.
* If ``M(d) = ('left', N)``, then the SubDomain spans a contiguous
  region of ``N`` points starting at ``d``'s left extreme.
* ``M(d) = ('right', N)`` is analogous to the case above.
* If ``M(d) = ('middle', N, M)``, then the SubDomain spans a contiguous
  region of ``d_size - (N + M)`` points starting at ``N`` and finishing
  at ``d_sizeM - M``.

Attributes

Name Type Description
separated bool, default=False Set to True to require a stencil-safe gap between opposite left/right regions, as in SubDimension, allowing concurrent scheduling when safe. By default, touching or overlapping regions are allowed. Applies to SubDimensions generated from tuple definitions; explicit Dimensions returned by :meth:define retain their own settings.

Examples

An “Inner” SubDomain, which spans the entire domain except for an exterior boundary region of thickness=3, can be implemented as follows

>>> from devito import SubDomain
>>> class Inner(SubDomain):
...     name = 'inner'
...     def define(self, dimensions):
...         return {d: ('middle', 3, 3) for d in dimensions}

Like before, but now spanning the entire y Dimension of a three-dimensional grid

>>> class InnerY(SubDomain):
...     name = 'inner_y'
...     def define(self, dimensions):
...         x, y, z = dimensions
...         return {x: ('middle', 3, 3), y: y, z: ('middle', 3, 3)}

To declare that opposite boundary regions leave a stencil-safe gap, set separated = True on the SubDomain subclass:

>>> class LeftBoundary(SubDomain):
...     name = 'left_boundary'
...     separated = True
...     def define(self, dimensions):
...         x, y = dimensions
...         return {x: ('left', 3), y: y}

See Also

Domain : An example of preset SubDomain. Interior : An example of preset Subdomain.

Notes

SubDomains are the only way to harness the benefits of domain decomposition, especially when defining BCs.

Methods

Name Description
define Parametrically describe the SubDomain w.r.t. a generic Grid.

define

define(dimensions)

Parametrically describe the SubDomain w.r.t. a generic Grid.

Notes

This method should be overridden by each SubDomain subclass. For more information, refer to SubDomain.__doc__.

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