Skip to content

Minor improvement to statistics.pdf() #148500

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

Merged
rhettinger merged 1 commit into from
Apr 13, 2026
+5 −4
Merged

Minor improvement to statistics.pdf() #148500

Changes from all commits
Commits
Show all changes
1 commit
Select commit
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: 5 additions & 4 deletions Lib/statistics.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -145,6 +145,7 @@
from collections import Counter, namedtuple, defaultdict

_SQRT2 = sqrt(2.0)
_SQRT2PI = sqrt(tau)
_random = random

## Exceptions ##############################################################
Expand Down Expand Up @@ -1257,11 +1258,11 @@ def samples(self, n, *, seed=None):

def pdf(self, x):
"Probability density function. P(x <= X < x+dx) / dx"
variance = self._sigma * self._sigma
if not variance:
sigma = self._sigma
if not sigma:
raise StatisticsError('pdf() not defined when sigma is zero')
diff = x - self._mu
return exp(diff * diff / (-2.0 * variance)) / sqrt(tau * variance)
z = (x - self._mu) / sigma
return exp(-0.5 * z * z) / (_SQRT2PI * sigma)

def cdf(self, x):
"Cumulative distribution function. P(X <= x)"
Expand Down
Loading