From f31e800755d84bc38d169b6668a86abdb2fe9a99 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marek=20Ne=C4=8Dada?= <marek@necada.org>
Date: Mon, 25 Feb 2019 12:21:38 +0200
Subject: [PATCH] Fix to irot3.isclose()

Former-commit-id: 5628e48141dac6dcc9726da999b6004b6cb445c9
---
 qpms/qpms_c.pyx | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/qpms/qpms_c.pyx b/qpms/qpms_c.pyx
index f4b9cff..0fb5630 100644
--- a/qpms/qpms_c.pyx
+++ b/qpms/qpms_c.pyx
@@ -855,5 +855,9 @@ cdef class irot3:
         '''
         if self.det != other.det: 
             return False
-        return self.rot.isclose(other.rot, rtol=rtol, atol=atol)
+        return (self.rot.isclose(other.rot, rtol=rtol, atol=atol)
+                # unit quaternions are a double cover of SO(3), i.e.
+                # minus the same quaternion represents the same rotation
+                or self.rot.isclose(-(other.rot), rtol=rtol, atol=atol)
+            )