fixed bug in hmatrix z vector calculation, added unittest

src/euston/geometry.py

@@ -37,7 +37,7 @@ def abc_to_hmatrix(a, b, c, alpha, beta, gamma, degrees=True):
     a = np.array((a, 0, 0))
     b = b*np.array((math.cos(gamma), math.sin(gamma),0))
     bracket = (math.cos(alpha)-math.cos(beta)*math.cos(gamma))/math.sin(gamma)
-    c = c*np.array((math.cos(beta), bracket, math.sin(beta)**2-bracket**2))
+    c = c*np.array((math.cos(beta), bracket, math.sqrt(math.sin(beta)**2-bracket**2)))
 
     result[:, 0] = a
     result[:, 1] = b

tests/data/test_geometry.py

@@ -14,15 +14,14 @@ def test_anglebetween(self):
         self.assertEqual(0, np.rad2deg(geo._angle_between(a, a)))
         self.assertEqual(180, np.rad2deg(geo._angle_between(a, -a)))
 
-    #def test_hmatabc(self):
-    #    """Tests whether alternating conversions are stable."""
-    #    def _docheck(self, test):
-    #        abc = np.array(test)
-    #        result = geo.hmatrix_to_abc(geo.abc_to_hmatrix(*abc, degrees=True), degrees=True)
-    #        print np.array(test)-result
-    #        self.assertTrue(np.allclose(np.array(test), result))
+    def test_hmatabc(self):
+        """Tests whether alternating conversions are stable."""
+        def _docheck(self, test):
+            abc = np.array(test)
+            result = geo.hmatrix_to_abc(geo.abc_to_hmatrix(*abc, degrees=True), degrees=True)
+            self.assertTrue(np.allclose(np.array(test), result))
 
-    #    _docheck(self, [1.1, 2.2, 3.3, 90,90,120])
-    #    _docheck(self, [1.1, 2.2, 3.3, 90,90,90])
+        _docheck(self, [1.1, 2.2, 3.3, 90,90,120])
+        _docheck(self, [1.1, 2.2, 3.3, 90,90,90])
         # triclinic: Chalcanthite
-    #    _docheck(self, [6.12, 10.72, 5.96, 82.4,107.3,102.6])
+        _docheck(self, [6.11, 10.673, 5.95, 97.58, 107.17, 77.55])