From: Michael Orlitzky <michael@orlitzky.com>
Date: Fri, 2 Nov 2018 00:41:49 +0000 (-0400)
Subject: cone/faces.py: add test for Proposition 3.1 and Corollary 3.9 in Tam.
X-Git-Url: https://gitweb.michael.orlitzky.com/?a=commitdiff_plain;h=c00b0cce43e8345d88097c74a3421f71e3b45e2b;p=sage.d.git

cone/faces.py: add test for Proposition 3.1 and Corollary 3.9 in Tam.
---

diff --git a/mjo/cone/faces.py b/mjo/cone/faces.py
index 70ecc20..8e5f243 100644
--- a/mjo/cone/faces.py
+++ b/mjo/cone/faces.py
@@ -105,6 +105,21 @@ def face_generated_by(K,S):
         sage: actual == expected
         True
 
+    Combining Proposition 3.1 and Corollary 3.9 in [Tam]_ gives the
+    following equality for any ``y`` in ``K``::
+
+        sage: set_random_seed()
+        sage: K = random_cone(max_ambient_dim=8, max_rays=10)
+        sage: y = K.random_element()
+        sage: S = [y]
+        sage: phi_y = face_generated_by(K,S)
+        sage: points_cone_gens = list(K.rays()) + [-z for z in phi_y.rays()]
+        sage: points_cone = Cone(points_cone_gens, K.lattice())
+        sage: actual = phi_y.span(QQ)
+        sage: expected = points_cone.linear_subspace()
+        sage: actual == expected
+        True
+
     """
     face_lattice = K.face_lattice()
     candidates = [F for F in face_lattice if all([F.contains(x) for x in S])]