Adding a factor to prefer not conjugating matrices so that the results are more stable across platforms.

Author: unhyperbolic

python/drilling/test_cases.py

@@ -38,12 +38,12 @@
 Tests drilling geodesics that are entirely in the 2-skeleton::
 
     >>> M.drill_words(['a','acAADa']).canonical_retriangulation().triangulation_isosig(ignore_orientation=False)
-    'ivvPQQcfhghgfghfaaaaaaaaa_BabBBbBaBBaBbbab'
+    'ivvPQQcfhghgfghfaaaaaaaaa_BabBBbBaBBaBbbBa'
 
 Same test as verified computation::
 
     sage: M.drill_words(['a','acAADa'], verified = True, bits_prec = 60).canonical_retriangulation().triangulation_isosig(ignore_orientation=False)
-    'ivvPQQcfhghgfghfaaaaaaaaa_BabBBbBaBBaBbbab'
+    'ivvPQQcfhghgfghfaaaaaaaaa_BabBBbBaBBaBbbBa'
 
 Test error when drilling something close to core curve::
 
@@ -70,7 +70,7 @@
 handled by 2-3 moves (in particular, commit f9879d04 introduced a bug):
 
     >>> Manifold("m004").drill_words(['CAC','CCbC']).canonical_retriangulation().triangulation_isosig(ignore_orientation=False)
-    'qLvvLvAMQQQkcgimopkllmpkonnnpixcaelchapewetvrn_bcaaBbBBbBaaBbB'
+    'qLvvLvAMQQQkcgimopkllmpkonnnpixcaelchapewetvrn_bcaaBbBBbaBaBbB'
 
 
 An interesting case where geodesic intersects triangulation in only one tetrahedron:
@@ -110,6 +110,12 @@
     Number of tets after subdividing: 69
     Shortening geodesic by sweeping across triangle.
     'mLALzLQMPbcbefjhhijkllxxnnxagbxnhhn_cbBabBcB'
+    >>> Manifold("m307").drill_word('dadadabCdada', verbose=True).isometry_signature(of_link=True) # doctest: +NUMERIC9
+    Tubes lower bound injectivity radius: 0.380575727319487
+    Number of geodesic pieces: [9]
+    Number of tets after subdividing: 45
+    Shortening geodesic by sweeping across triangle.
+    'oLLwQvvPQQcbeefgemnllnmnmlhhaaaaaahaaaaah_bBbabaab'
     >>> Manifold("m307").drill_word('ADADcBADADAD', verbose=True).isometry_signature(of_link=True) # doctest: +NUMERIC9
     Tubes lower bound injectivity radius: 0.380575727319372
     Number of geodesic pieces: [9]

python/geometric_structure/geodesic/fixed_points.py

@@ -9,6 +9,8 @@
 __all__ = ['r13_fixed_points_of_psl2c_matrix',
            'r13_fixed_line_of_psl2c_matrix']
 
+_pref_factor = 64
+
 def r13_fixed_points_of_psl2c_matrix(m):
     """
     Given a PSL(2,C)-matrix m acting on the upper halfspace model,
@@ -22,15 +24,15 @@ def r13_fixed_points_of_psl2c_matrix(m):
     # a fixed matrix t.
 
     # To decide whether to conjugate, we compare m[1,0] with
-    # the value m[1,0] has after conjugating.
+    # the value m[1,0] has after conjugating - with a factor to prefer not
+    # to conjugate.
 
-    abs_c = _lower_bound_abs(m[1,0])
+    abs_c = _lower_bound_abs(m[1,0]) * _pref_factor
 
     bc = m[1,0] - m[0,1]
     ad = m[1,1] - m[0,0]
     abs_c_pm_m_pp = _lower_bound_abs(bc + ad)
     abs_c_pp_m_pm = _lower_bound_abs(bc - ad)
-
     if abs_c > abs_c_pm_m_pp and abs_c > abs_c_pp_m_pm:
         return _r13_fixed_points_of_psl2c_matrix(m)