Merge pull request #146 from skirpichev/fix-10198

Allow negative powers of abs in the reduce_abs_inequality
diofant · Dec 8, 2015 · 3cdc368 · 3cdc368
2 parents 697a2a2 + e99fb23
commit 3cdc368
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Showing 2 changed files with 6 additions and 3 deletions.
diff --git a/sympy/solvers/inequalities.py b/sympy/solvers/inequalities.py
@@ -317,9 +317,8 @@ def _bottom_up_scan(expr):
         elif expr.is_Pow:
             n = expr.exp
 
-            if not n.is_Integer or n < 0:
-                raise ValueError(
-                    "only non-negative integer powers are allowed")
+            if not n.is_Integer:
+                raise NotImplementedError("only integer powers are supported")
 
             _exprs = _bottom_up_scan(expr.base)
 

diff --git a/sympy/solvers/tests/test_inequalities.py b/sympy/solvers/tests/test_inequalities.py
@@ -186,6 +186,10 @@ def test_reduce_abs_inequalities():
     nr = Symbol('nr', extended_real=False)
     raises(TypeError, lambda: reduce_inequalities(abs(nr - 5) < 3))
 
+    # sympy/sympy#10198
+    assert reduce_inequalities(-1 + 1/abs(1/x - 1) < 0) == \
+        Or(And(S.Zero < x, x < S.Half), And(-oo < x, x < S.Zero))
+
 
 def test_reduce_inequalities_general():
     assert reduce_inequalities(Ge(sqrt(2)*x, 1)) == And(sqrt(2)/2 <= x, x < oo)