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[Darren Dale <dsdale24@xxxxxxxxx>]

** Changed in: python-quantities
       Status: Fix Committed => Fix Released

-- 
Dividing by UncertainQuantity returns wrong uncertainty value
https://bugs.launchpad.net/bugs/402830
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Status in Physical Quantities for Python: Fix Released

Bug description:
Dividing by an UncertainQuantity doesn't give consistent behavior. For example,
when both the numerator and denomenator are UncertainQuantities, the uncertainty is correct
>>> import quantities as pq
>>> t = pq.UncertainQuantity(1, pq.s, 0.1)
>>> print pq.UncertainQuantity(1) / t
1.0 1/s
±0.1 1/s (1σ)

When only the denomenator is an UncertainQuantity, the uncertainty blows up:
>>> t = pq.UncertainQuantity(1, pq.s, 0.1)
>>> print pq.Quantity(1) / t
1.0 1/s
±10.0 1/s (1σ)

A simple patch is attached below. An alternative patch would convert `other` to an UncertainQuantity and reuse `__truediv__`.

=== modified file 'quantities/tests/test_60_uncertainty.py'
--- quantities/tests/test_60_uncertainty.py	2009-06-18 21:11:08 +0000
+++ quantities/tests/test_60_uncertainty.py	2009-07-22 01:35:49 +0000
@@ -81,3 +81,7 @@
         str(a/2),
         '[ 0.5  1. ] m\n±[ 0.05  0.1 ] m (1σ)'
     )
+    assert_equal(
+        str(1/a),
+        '[ 1.   0.5] 1/m\n±[ 0.1   0.05] 1/m (1σ)'
+    )

=== modified file 'quantities/uncertainquantity.py'
--- quantities/uncertainquantity.py	2009-06-18 20:54:16 +0000
+++ quantities/uncertainquantity.py	2009-07-22 02:24:12 +0000
@@ -148,7 +148,7 @@
     def __rtruediv__(self, other):
         temp = UncertainQuantity(
             1/self.magnitude, self.dimensionality**-1,
-            1/self.uncertainty.magnitude, copy=False
+            self.relative_uncertainty/self.magnitude, copy=False
         )
         return other * temp