Merge pull request #435 from fchapoton/patch-1

fix doc error in _multivector.py

clifford/_multivector.py

@@ -849,7 +849,7 @@ def dual(self, I=None) -> 'MultiVector':
     def commutator(self, other) -> 'MultiVector':
         r"""The commutator product of two multivectors.
 
-        :math:`[M, N] = M \times N = (MN + NM)/2`
+        :math:`[M, N] = M \times N = (MN - NM)/2`
         """
 
         return ((self * other) - (other * self)) / 2