fdtdx.UniformGrid

class fdtdx.UniformGrid(*, spacing=null, center=(0, 0, 0))

Bases: TreeClass

Unresolved policy for a uniform rectilinear grid.

UniformGrid is user intent, not the solver mesh itself. It records the physical cell spacing while the final simulation shape may still be unknown. Object placement resolves this policy to a concrete RectilinearGrid once the volume shape is known.

Keeping uniform spacing here avoids a second scalar discretization source on SimulationConfig. Uniform grids and explicitly non-uniform grids both enter the solver through the same realized RectilinearGrid structure.

The grid origin is at the center of the simulation domain. Edge arrays therefore span [-N/2 * spacing, +N/2 * spacing] along each axis, giving the domain symmetric negative and positive coordinates. center shifts this physical center away from the geometric origin when non-zero.

Quick Reference

Attributes

• center

• is_uniform

• min_spacing

• spacing

• uniform_spacing

Methods

• anchor_coordinate

• aset

• axis_extent

• bounds_for_anchor

• bounds_for_center

• cell_volume

• coord_to_index

• face_area

• get_class_fields

• get_public_fields

• length_to_cell_count

• resolve

• slice_extent

Attributes

UniformGrid.center: tuple[float, float, float]

Physical coordinate of the domain center in metres. Defaults to (0, 0, 0).

UniformGrid.is_uniform

Uniform policies always represent equal cell widths.

UniformGrid.min_spacing

Smallest cell width implied by this policy.

UniformGrid.spacing: float

Physical cell spacing in metres. Must be positive.

UniformGrid.uniform_spacing

Scalar cell width in metres.

Methods

UniformGrid.anchor_coordinate(axis, bounds, position)

Return a physical anchor coordinate inside a uniform interval.

Return type:

float

UniformGrid.aset(attr_name, val, create_new_ok=False)

Sets an attribute of this class. In contrast to the classical .at[].set(), this method updates the class attribute directly and does not only operate on jax pytree leaf nodes. Instead, replaces the full attribute with the new value.

The attribute can either be the attribute name of this class, or for nested classes it can also be the attribute name of a class, which itself is an attribute of this class. The syntax for this operation could look like this: “a->b->[0]->[‘name’]”. Here, the current class has an attribute a, which has an attribute b, which is a list, which we index at index 0, which is an element of type dictionary, which we index using the dictionary key ‘name’.

Note that dictionary keys cannot contain square brackets or single quotes (even if they are escaped).

Parameters:

• attr_name (str) – Name of attribute to set

• val (Any) – Value to set the attribute to

• create_new_ok (bool, optional) – If false (default), throw an error if the attribute does not exist. If true, creates a new attribute if the attribute name does not exist yet.

Returns:

Updated instance with new attribute value

Return type:

Self

UniformGrid.axis_extent(axis, bounds)

Physical length covered by an index interval on one axis.

Return type:

float

UniformGrid.bounds_for_anchor(axis, size, anchor, position)

Choose a uniform-grid interval from an object anchor.

Return type:

tuple[int, int]

UniformGrid.bounds_for_center(axis, center, size)

Convert a physical center and grid size to edge bounds.

Return type:

tuple[int, int]

UniformGrid.cell_volume(slice_tuple)

Return per-cell volumes for a slice on this uniform policy.

Return type:

Array

UniformGrid.coord_to_index(axis, coord, snap='nearest')

Map a physical coordinate to a uniform-grid edge index.

Because unresolved policies do not yet know shape, this helper uses a center-relative basis: coord is interpreted relative to self.center[axis] and the returned index is a center-relative edge offset. Use RectilinearGrid.coord_to_index() on the resolved grid when you need absolute edge indices.

Return type:

int

UniformGrid.face_area(axis, slice_tuple)

Return per-face areas for a slice on this uniform policy.

Return type:

Array

UniformGrid.get_class_fields()

Return type:

list[TreeClassField]

UniformGrid.get_public_fields()

Return type:

list[TreeClassField]

UniformGrid.length_to_cell_count(axis, length, snap='nearest')

Convert a physical length to a uniform-grid cell count.

Return type:

int

UniformGrid.resolve(shape)

Return a concrete solver grid for shape.

Return type:

RectilinearGrid

UniformGrid.slice_extent(slice_tuple)

Physical side lengths covered by a 3D grid slice.

Return type:

tuple[float, float, float]

If you find any errors in the documentation, please report them in the Github Issues!