fix: GBS now carries over previous orientation

Fixes the grain boundary sliding routine to match what is defined in the
original fortran, where dotacs and rot are set to zero for grains that
are sliding, i.e. there is zero rotation _rate_, but not resetting the
whole orientation matrix to the initial one. Now simply carries over the
previous orientation.

Also adds symmetry asserts to the GBS test.

src/pydrex/minerals.py

@@ -362,8 +362,7 @@ def apply_gbs(orientations, fractions, config):
                 len(np.nonzero(mask)) / len(fractions),
             )
             # No rotation: carry over previous orientations.
-            # TODO: Should we really be resetting to initial orientations here?
-            orientations[mask, :, :] = self.orientations[0][mask, :, :]
+            orientations[mask, :, :] = self.orientations[-1][mask, :, :]
             fractions[mask] = config["gbs_threshold"] / self.n_grains
             fractions /= fractions.sum()
             _log.debug(

src/pydrex/visualisation.py

@@ -125,27 +125,6 @@ def polefigures(
     fig.savefig(_io.resolve_path(savefile))
 
 
-def check_marker_seq(func):
-    """Raises a `ValueError` if number of markers and data series don't match.
-
-    The decorated function is expected to take the data as the first positional
-    argument, and a keyword argument called `markers`.
-
-    """
-
-    @ft.wraps(func)
-    def wrapper(data, *args, **kwargs):
-        markers = kwargs["markers"]
-        if len(data) % len(markers) != 0:
-            raise ValueError(
-                "Number of data series must be divisible by number of markers."
-                + f" You've supplied {len(data)} data series and {len(markers)} markers."
-            )
-        func(data, *args, **kwargs)
-
-    return wrapper
-
-
 def _get_marker_and_label(data, seq_index, markers, labels=None):
     marker = markers[int(seq_index / (len(data) / len(markers)))]
     label = None
@@ -154,7 +133,6 @@ def _get_marker_and_label(data, seq_index, markers, labels=None):
     return marker, label
 
 
-@check_marker_seq
 def simple_shear_stationary_2d(
     strains,
     target_angles,
@@ -214,7 +192,6 @@ def _lag_2d_corner_flow(θ):
     )
 
 
-@check_marker_seq
 def corner_flow_2d(
     x_paths,
     z_paths,

tests/test_simple_shear_2d.py

@@ -219,9 +219,9 @@ def get_velocity_gradient(x):
 
     def test_dudz_GBS(
         self,
-        params_Kaminski2004_fig4_triangles,  # GBS = 0.4
-        params_Kaminski2004_fig4_squares,  # GBS = 0.2
         params_Kaminski2004_fig4_circles,  # GBS = 0
+        params_Kaminski2004_fig4_squares,  # GBS = 0.2
+        params_Kaminski2004_fig4_triangles,  # GBS = 0.4
         rng,
         outdir,
     ):
@@ -232,10 +232,10 @@ def test_dudz_GBS(
 
         """
         strain_rate = 5e-6  # Strain rate from Fraters & Billen, 2021, fig. 3.
-        timestamps = np.linspace(0, 5e5, 201)  # Solve until D₀t=2.5 ('shear' γ=5).
+        timestamps = np.linspace(0, 5e5, 251)  # Solve until D₀t=2.5 ('shear' γ=5).
         n_timesteps = len(timestamps)
         i_first_cpo = 50  # First index where Bingham averages are sufficiently stable.
-        i_strain_50p = [0, 50, 100, 150, 200]  # Indices for += 50% strain.
+        i_strain_100p = [0, 50, 100, 150, 200]  # Indices for += 100% strain.
 
         def get_velocity_gradient(x):
             # It is independent of time or position in this test.
@@ -258,9 +258,9 @@ def get_velocity_gradient(x):
         with optional_logging:
             for p, params in enumerate(
                 (
-                    params_Kaminski2004_fig4_triangles,  # GBS = 0.4
-                    params_Kaminski2004_fig4_squares,  # GBS = 0.2
                     params_Kaminski2004_fig4_circles,  # GBS = 0
+                    params_Kaminski2004_fig4_squares,  # GBS = 0.2
+                    params_Kaminski2004_fig4_triangles,  # GBS = 0.4
                 ),
             ):
                 mineral = _minerals.Mineral(
@@ -369,3 +369,23 @@ def get_velocity_gradient(x):
         # We want the angle from the Y axis (shear direction), so subtract from 90.
         θ_fse_eq = [90 - _utils.angle_fse_simpleshear(strain) for strain in strains]
         nt.assert_allclose(θ_fse, θ_fse_eq, rtol=1e-7, atol=0)
+
+        # Check point symmetry of [100] at strains of 0%, 100%, 200%, 300% & 400%.
+        nt.assert_allclose(
+            [0.015, 0.52, 0.86, 0.93, 0.94],
+            point100_symmetry[0].take(i_strain_100p),
+            rtol=0,
+            atol=0.015,
+        )
+        nt.assert_allclose(
+            [0.015, 0.4, 0.72, 0.77, 0.79],
+            point100_symmetry[1].take(i_strain_100p),
+            rtol=0,
+            atol=0.015,
+        )
+        nt.assert_allclose(
+            [0.015, 0.39, 0.58, 0.61, 0.62],
+            point100_symmetry[2].take(i_strain_100p),
+            rtol=0,
+            atol=0.015,
+        )