Fix surface refinement

[inducer]

This adds a failing test for the ability to refine toruses and spheres without large node-vertex inconsistencies.

I'm guessing this might have to do with the work in #97. I don't yet fully understand what's going on.

cc @alexfikl

[alexfikl]

What's supposed to fail? It works locally.

[inducer]

I get

Traceback (most recent call last):
  File "/home/andreas/src/meshmode/test/test_refinement.py", line 360, in <module>
    exec(sys.argv[1])
  File "<string>", line 1, in <module>
  File "/home/andreas/src/meshmode/test/test_refinement.py", line 349, in test_refine_surfaces
    refined_mesh = refine_uniformly(mesh, 1)
  File "/home/andreas/src/meshmode/meshmode/mesh/refinement/__init__.py", line 991, in refine_uniformly
    refiner.refine_uniformly()
  File "/home/andreas/src/meshmode/meshmode/mesh/refinement/no_adjacency.py", line 61, in refine_uniformly
    return self.refine(flags)
  File "/home/andreas/src/meshmode/meshmode/mesh/refinement/no_adjacency.py", line 227, in refine
    new_mesh = Mesh(new_vertices, new_el_groups, is_conforming=(
  File "/home/andreas/src/meshmode/meshmode/mesh/__init__.py", line 779, in __init__
    assert _test_node_vertex_consistency(
  File "/home/andreas/src/meshmode/meshmode/mesh/__init__.py", line 983, in _test_node_vertex_consistency
    assert _test_node_vertex_consistency_resampling(mesh, mgrp, tol)
  File "/home/andreas/src/meshmode/meshmode/mesh/__init__.py", line 971, in _test_node_vertex_consistency_resampling
    assert max_el_vertex_error < tol*size, max_el_vertex_error
AssertionError: 9.901371953343942

Strangely, that seems to reproduce on my laptop and nowhere else.

[alexfikl]

Hm, I've added a refine_uniformly to various surface tests in test_meshmode.py too and couldn't get any of them to fail (ran multiple times).

Does it fail for both the sphere and the torus?

[inducer]

Does it fail for both the sphere and the torus?

Yeah. The fact that CI passed is further indication that this might me something to do with my environment. I'll need to investigate. Thanks for helping!

[inducer]

inducer/pytential#63 is another thing that seems to be unique to my laptop. Kind of weird.

[inducer]

Very strangely, this works OK on my laptop in an environment based on conda.

[alexfikl]

Very strangely, this works OK on my laptop in an environment based on conda.

I'm not using conda locally, just good old venv with master from pretty much everything.

[inducer]

On my laptop: Rebuilt my venv with the existing source trees... same result. Freshly downloaded source with fresh venv... also same result.

On dunkel: Freshly downloaded source with fresh venv... no error.