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Drop support for scalar-only broadcasting in dt_utils #370

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Drop support for scalar-only broadcasting in dt_utils #370

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59 changes: 19 additions & 40 deletions grudge/dt_utils.py
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Original file line number Diff line number Diff line change
Expand Up @@ -296,50 +296,29 @@ def dt_geometric_factors(
)
)

if actx.supports_nonscalar_broadcasting:
# Compute total surface area of an element by summing over the
# individual face areas
surface_areas = DOFArray(
actx,
data=tuple(
actx.einsum(
"fej->e",
tag_axes(actx, {
0: DiscretizationFaceAxisTag(),
1: DiscretizationElementAxisTag(),
2: DiscretizationDOFAxisTag()
},
face_ae_i.reshape(
vgrp.mesh_el_group.nfaces,
vgrp.nelements,
face_ae_i.shape[-1])),
tagged=(FirstAxisIsElementsTag(),))

for vgrp, face_ae_i in zip(volm_discr.groups, face_areas, strict=True)))
else:
surface_areas = DOFArray(
actx,
data=tuple(
# NOTE: Whenever the array context can't perform nonscalar
# broadcasting, elementwise reductions
# (like `elementwise_integral`) repeat the *same* scalar value of
# the reduction at each degree of freedom. To get a single
# value for the face area (per face),
# we simply average over the nodes, which gives the desired result.
actx.einsum(
"fej->e",
if not actx.supports_nonscalar_broadcasting:
raise ValueError("Array context does not allow advanced indexing. "
"This is no longer supported.")

# Compute total surface area of an element by summing over the
# individual face areas
surface_areas = DOFArray(
actx,
data=tuple(
actx.einsum(
"fej->e",
tag_axes(actx, {
0: DiscretizationFaceAxisTag(),
1: DiscretizationElementAxisTag(),
2: DiscretizationDOFAxisTag()
},
face_ae_i.reshape(
vgrp.mesh_el_group.nfaces,
vgrp.nelements,
face_ae_i.shape[-1]
) / afgrp.nunit_dofs,
tagged=(FirstAxisIsElementsTag(),))
face_ae_i.shape[-1])),
tagged=(FirstAxisIsElementsTag(),))

for vgrp, afgrp, face_ae_i in zip(volm_discr.groups,
face_discr.groups,
face_areas, strict=True)
)
)
for vgrp, face_ae_i in zip(volm_discr.groups, face_areas, strict=True)))

return actx.freeze(
actx.tag(NameHint(f"dt_geometric_{dd.as_identifier()}"),
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