Increasing the Coverage

lbmpy/equilibrium/generic_discrete_equilibrium.py

@@ -19,7 +19,7 @@ def discrete_equilibrium_from_matching_moments(stencil, moment_constraints,
         return GenericDiscreteEquilibrium(stencil, pdfs, zeroth_order_moment_symbol,
                                           first_order_moment_symbols, deviation_only=deviation_only)
     except sp.matrices.inverse.NonInvertibleMatrixError as e:
-        raise Exception("Could not construct equilibrium from given moment constraints.") from e
+        raise ValueError("Could not construct equilibrium from given moment constraints.") from e
 
 
 class GenericDiscreteEquilibrium(AbstractEquilibrium):

lbmpy_tests/test_hydro_maxwellian_class.py

@@ -2,6 +2,8 @@ import pytest
 import sympy as sp
 from itertools import chain
 
+from pystencils.sympyextensions import remove_higher_order_terms
+
 from lbmpy.stencils import Stencil, LBStencil
 from lbmpy.equilibrium import ContinuousHydrodynamicMaxwellian, DiscreteHydrodynamicMaxwellian
 from lbmpy.moments import moments_up_to_component_order, moments_up_to_order
@@ -73,3 +75,51 @@ def test_continuous_discrete_moment_equivalence(stencil, compressible, deviation
     subs = { delta_rho : rho - rho_0 }
 
     assert (cm - dm).subs(subs).expand() == sp.Matrix((0,) * len(moments))
+
+
+@pytest.mark.parametrize('stencil', [Stencil.D2Q9, Stencil.D3Q15, Stencil.D3Q19, Stencil.D3Q27])
+@pytest.mark.parametrize('compressible', [False, True])
+@pytest.mark.parametrize('deviation_only', [False, True])
+def test_continuous_discrete_central_moment_equivalence(stencil, compressible, deviation_only):
+    stencil = LBStencil(stencil)
+    c_s_sq = sp.Rational(1, 3)
+    moments = tuple(moments_up_to_order(3, dim=stencil.D, include_permutations=False))
+    cd = ContinuousHydrodynamicMaxwellian(dim=stencil.D, compressible=compressible, deviation_only=deviation_only,
+                                          order=2, c_s_sq=c_s_sq)
+    cm = sp.Matrix(cd.central_moments(moments))
+    dd = DiscreteHydrodynamicMaxwellian(stencil, compressible=compressible, deviation_only=deviation_only,
+                                        order=2, c_s_sq=c_s_sq)
+    dm = sp.Matrix(dd.central_moments(moments))
+    dm = sp.Matrix([remove_higher_order_terms(t, dd.velocity, order=2) for t in dm])
+
+    rho = cd.density
+    delta_rho = cd.density_deviation
+    rho_0 = cd.background_density
+
+    subs = { delta_rho : rho - rho_0 }
+
+    assert (cm - dm).subs(subs).expand() == sp.Matrix((0,) * len(moments))
+
+
+@pytest.mark.parametrize('stencil', [Stencil.D2Q9, Stencil.D3Q15, Stencil.D3Q19, Stencil.D3Q27])
+def test_continuous_discrete_cumulant_equivalence(stencil):
+    stencil = LBStencil(stencil)
+    c_s_sq = sp.Rational(1, 3)
+    compressible = True
+    deviation_only = False
+    moments = tuple(moments_up_to_order(3, dim=stencil.D, include_permutations=False))
+    cd = ContinuousHydrodynamicMaxwellian(dim=stencil.D, compressible=compressible, deviation_only=deviation_only,
+                                          order=2, c_s_sq=c_s_sq)
+    cm = sp.Matrix(cd.cumulants(moments))
+    dd = DiscreteHydrodynamicMaxwellian(stencil, compressible=compressible, deviation_only=deviation_only,
+                                        order=2, c_s_sq=c_s_sq)
+    dm = sp.Matrix(dd.cumulants(moments))
+    dm = sp.Matrix([remove_higher_order_terms(t, dd.velocity, order=2) for t in dm])
+
+    rho = cd.density
+    delta_rho = cd.density_deviation
+    rho_0 = cd.background_density
+
+    subs = { delta_rho : rho - rho_0 }
+
+    assert (cm - dm).subs(subs).expand() == sp.Matrix((0,) * len(moments))

pytest.ini

@@ -30,6 +30,7 @@ exclude_lines =
        pragma: no cover
 
        def __repr__
+       def _repr_html_
 
        # Don't complain if tests don't hit defensive assertion code:
        raise AssertionError