[Python-checkins] cpython (2.7): Issue #17149: Fix random.vonmisesvariate to always return results in [0,
mark.dickinson
python-checkins at python.org
Sun Feb 10 15:17:42 CET 2013
http://hg.python.org/cpython/rev/6a3d18cede49
changeset: 82129:6a3d18cede49
branch: 2.7
parent: 82122:010b455de0e0
user: Mark Dickinson <dickinsm at gmail.com>
date: Sun Feb 10 14:13:40 2013 +0000
summary:
Issue #17149: Fix random.vonmisesvariate to always return results in [0, 2*math.pi].
files:
Lib/random.py | 4 ++--
Lib/test/test_random.py | 14 ++++++++++++++
Misc/NEWS | 3 +++
3 files changed, 19 insertions(+), 2 deletions(-)
diff --git a/Lib/random.py b/Lib/random.py
--- a/Lib/random.py
+++ b/Lib/random.py
@@ -475,9 +475,9 @@
u3 = random()
if u3 > 0.5:
- theta = (mu % TWOPI) + _acos(f)
+ theta = (mu + _acos(f)) % TWOPI
else:
- theta = (mu % TWOPI) - _acos(f)
+ theta = (mu - _acos(f)) % TWOPI
return theta
diff --git a/Lib/test/test_random.py b/Lib/test/test_random.py
--- a/Lib/test/test_random.py
+++ b/Lib/test/test_random.py
@@ -533,6 +533,20 @@
self.assertAlmostEqual(s1/N, mu, 2)
self.assertAlmostEqual(s2/(N-1), sigmasqrd, 2)
+ def test_von_mises_range(self):
+ # Issue 17149: von mises variates were not consistently in the
+ # range [0, 2*PI].
+ g = random.Random()
+ N = 100
+ for mu in 0.0, 0.1, 3.1, 6.2:
+ for kappa in 0.0, 2.3, 500.0:
+ for _ in range(N):
+ sample = g.vonmisesvariate(mu, kappa)
+ self.assertTrue(
+ 0 <= sample <= random.TWOPI,
+ msg=("vonmisesvariate({}, {}) produced a result {} out"
+ " of range [0, 2*pi]").format(mu, kappa, sample))
+
class TestModule(unittest.TestCase):
def testMagicConstants(self):
self.assertAlmostEqual(random.NV_MAGICCONST, 1.71552776992141)
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -202,6 +202,9 @@
Library
-------
+- Issue #17149: Fix random.vonmisesvariate to always return results in
+ the range [0, 2*math.pi].
+
- Issue #1470548: XMLGenerator now works with UTF-16 and UTF-32 encodings.
- Issue #6975: os.path.realpath() now correctly resolves multiple nested
--
Repository URL: http://hg.python.org/cpython
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