Issue #9920: Skip tests for cmath.atan and cmath.atanh applied to
complex zeros on systems where the log1p function fails to respect
the sign of zero. This fixes a test failure on AIX.
diff --git a/Lib/test/cmath_testcases.txt b/Lib/test/cmath_testcases.txt
index ce03232..9b08653 100644
--- a/Lib/test/cmath_testcases.txt
+++ b/Lib/test/cmath_testcases.txt
@@ -733,10 +733,11 @@
---------------------------
-- zeros
-atan0000 atan 0.0 0.0 -> 0.0 0.0
-atan0001 atan 0.0 -0.0 -> 0.0 -0.0
-atan0002 atan -0.0 0.0 -> -0.0 0.0
-atan0003 atan -0.0 -0.0 -> -0.0 -0.0
+-- These are tested in testAtanSign in test_cmath.py
+-- atan0000 atan 0.0 0.0 -> 0.0 0.0
+-- atan0001 atan 0.0 -0.0 -> 0.0 -0.0
+-- atan0002 atan -0.0 0.0 -> -0.0 0.0
+-- atan0003 atan -0.0 -0.0 -> -0.0 -0.0
-- values along both sides of imaginary axis
atan0010 atan 0.0 -9.8813129168249309e-324 -> 0.0 -9.8813129168249309e-324
@@ -896,10 +897,11 @@
---------------------------------------
-- zeros
-atanh0000 atanh 0.0 0.0 -> 0.0 0.0
-atanh0001 atanh 0.0 -0.0 -> 0.0 -0.0
-atanh0002 atanh -0.0 0.0 -> -0.0 0.0
-atanh0003 atanh -0.0 -0.0 -> -0.0 -0.0
+-- These are tested in testAtanhSign in test_cmath.py
+-- atanh0000 atanh 0.0 0.0 -> 0.0 0.0
+-- atanh0001 atanh 0.0 -0.0 -> 0.0 -0.0
+-- atanh0002 atanh -0.0 0.0 -> -0.0 0.0
+-- atanh0003 atanh -0.0 -0.0 -> -0.0 -0.0
-- values along both sides of real axis
atanh0010 atanh -9.8813129168249309e-324 0.0 -> -9.8813129168249309e-324 0.0
diff --git a/Lib/test/test_cmath.py b/Lib/test/test_cmath.py
index 0d12635..168b513 100644
--- a/Lib/test/test_cmath.py
+++ b/Lib/test/test_cmath.py
@@ -514,6 +514,24 @@
for z in complex_zeros:
self.assertComplexIdentical(cmath.tanh(z), z)
+ # The algorithm used for atan and atanh makes use of the system
+ # log1p function; If that system function doesn't respect the sign
+ # of zero, then atan and atanh will also have difficulties with
+ # the sign of complex zeros.
+ @requires_IEEE_754
+ @unittest.skipIf(sysconfig.get_config_var('LOG1P_DROPS_ZERO_SIGN'),
+ "system log1p() function doesn't preserve the sign")
+ def testAtanSign(self):
+ for z in complex_zeros:
+ self.assertComplexIdentical(cmath.atan(z), z)
+
+ @requires_IEEE_754
+ @unittest.skipIf(sysconfig.get_config_var('LOG1P_DROPS_ZERO_SIGN'),
+ "system log1p() function doesn't preserve the sign")
+ def testAtanhSign(self):
+ for z in complex_zeros:
+ self.assertComplexIdentical(cmath.atanh(z), z)
+
def test_main():
run_unittest(CMathTests)
diff --git a/Misc/NEWS b/Misc/NEWS
index 917b7cd..672d918 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -21,6 +21,10 @@
Library
-------
+- Issue #9920: Skip tests for cmath.atan and cmath.atanh applied to
+ complex zeros on systems where the log1p function fails to respect
+ the sign of zero. This fixes a test failure on AIX.
+
- Issue #10446: Module documentation generated by pydoc now links to a
version-specific online reference manual.