Skip to content

gh-135647: fix random.vonmisesvariate() and random.lognormvariate() accept invalid parameters #135717

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 2 commits into
base: main
Choose a base branch
from
+14 −4
Open

gh-135647: fix random.vonmisesvariate() and random.lognormvariate() accept invalid parameters #135717

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
749d105
gh-135647: fix random.vonmisesvariate() and random.lognormvariate() a…
michaelzheng67 Jun 19, 2025
42abd61
Merge branch 'main' into fix-issue-135647
tim-one Jun 21, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
9 changes: 8 additions & 1 deletion Lib/random.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -536,6 +536,8 @@ def triangular(self, low=0.0, high=1.0, mode=None):
def normalvariate(self, mu=0.0, sigma=1.0):
"""Normal distribution.
Conditions on the parameters are sigma > 0.
mu is the mean, and sigma is the standard deviation.
"""
Expand All @@ -544,6 +546,9 @@ def normalvariate(self, mu=0.0, sigma=1.0):
# variables using the ratio of uniform deviates", ACM Trans
# Math Software, 3, (1977), pp257-260.

if sigma <= 0:
raise ValueError("normalvariate: sigma must be > 0.0")

random = self.random
while True:
u1 = random()
Expand Down Expand Up @@ -640,7 +645,9 @@ def vonmisesvariate(self, mu, kappa):

random = self.random
if kappa <= 1e-6:
return TWOPI * random()
if kappa >= 0:
return TWOPI * random()
raise ValueError("vonmisesvariate: kappa must be >= 0.0")

s = 0.5 / kappa
r = s + _sqrt(1.0 + s * s)
Expand Down
9 changes: 6 additions & 3 deletions Lib/test/test_random.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1084,9 +1084,6 @@ def test_constant(self):
(g.expovariate, (float('inf'),), 0.0),
(g.vonmisesvariate, (3.0, float('inf')), 3.0),
(g.gauss, (10.0, 0.0), 10.0),
(g.lognormvariate, (0.0, 0.0), 1.0),
(g.lognormvariate, (-float('inf'), 0.0), 0.0),
(g.normalvariate, (10.0, 0.0), 10.0),
(g.binomialvariate, (0, 0.5), 0),
(g.binomialvariate, (10, 0.0), 0),
(g.binomialvariate, (10, 1.0), 10),
Expand Down Expand Up @@ -1152,7 +1149,13 @@ def test_binomialvariate(self):
# Demonstrate the BTRS works for huge values of n
self.assertTrue(19_000_000 <= B(100_000_000, 0.2) <= 21_000_000)
self.assertTrue(89_000_000 <= B(100_000_000, 0.9) <= 91_000_000)
def test_log_norm_errors(self):
# sigma must be > 0.0
self.assertRaises(ValueError, random.lognormvariate, 1, -2)

def test_von_mises_errors(self):
# kappa must be >= 0.0
self.assertRaises(ValueError, random.vonmisesvariate, 1, -2)

def test_von_mises_range(self):
# Issue 17149: von mises variates were not consistently in the
Expand Down
Loading