Ticket #12345: trac_12345_minusinfinity_sympyfication.patch

sage/rings/infinity.py

@@ -1193 +1193 @@
         """
         raise SignError, "cannot take square root of negative infinity"
 
+    def _sympy_(self):
+        """
+        Converts -oo to sympy -oo.
+        
+        Then you don't have to worry which oo you use, like in these
+        examples:
+        
+        EXAMPLE::
+        
+            sage: import sympy
+            sage: bool(-oo == -sympy.oo) 
+            True
+            sage: bool(SR(-oo) == -sympy.oo)
+            True
+            sage: bool((-oo)._sympy_() == -sympy.oo)
+            True
+
+        """
+        import sympy
+        return -sympy.oo
+
+
 class PlusInfinity(_uniq, AnInfinity, PlusInfinityElement):
 
     _sign = 1

sage/symbolic/integration/integral.py

@@ -662 +662 @@
         sage: F(x=1, a=7).numerical_approx() # abs tol 1e-10
         4.32025625668262
 
+    Verify that MinusInfinity works with sympy (:trac:`12345`)::
+    
+        sage: integral(1/x^2, x, -infinity, -1, algorithm='sympy')
+        1
+
     """
     expression, v, a, b = _normalize_integral_input(expression, v, a, b)
     if algorithm is not None: