[Python-checkins] log2() is faster than log() (#95214)

rhettinger webhook-mailer at python.org
Sun Jul 24 15:21:33 EDT 2022


https://github.com/python/cpython/commit/eb9c8a8bea9128b31d4a604c4a1f27ec9b45f333
commit: eb9c8a8bea9128b31d4a604c4a1f27ec9b45f333
branch: main
author: Raymond Hettinger <rhettinger at users.noreply.github.com>
committer: rhettinger <rhettinger at users.noreply.github.com>
date: 2022-07-24T14:21:29-05:00
summary:

log2() is faster than log() (#95214)

files:
M Lib/random.py

diff --git a/Lib/random.py b/Lib/random.py
index ef0034adce5e7..76627309e288b 100644
--- a/Lib/random.py
+++ b/Lib/random.py
@@ -50,7 +50,7 @@
 from math import log as _log, exp as _exp, pi as _pi, e as _e, ceil as _ceil
 from math import sqrt as _sqrt, acos as _acos, cos as _cos, sin as _sin
 from math import tau as TWOPI, floor as _floor, isfinite as _isfinite
-from math import lgamma as _lgamma, fabs as _fabs
+from math import lgamma as _lgamma, fabs as _fabs, log2 as _log2
 from os import urandom as _urandom
 from _collections_abc import Sequence as _Sequence
 from operator import index as _index
@@ -764,11 +764,11 @@ def binomialvariate(self, n=1, p=0.5):
             # BG: Geometric method by Devroye with running time of O(np).
             # https://dl.acm.org/doi/pdf/10.1145/42372.42381
             x = y = 0
-            c = _log(1.0 - p)
+            c = _log2(1.0 - p)
             if not c:
                 return x
             while True:
-                y += _floor(_log(random()) / c) + 1
+                y += _floor(_log2(random()) / c) + 1
                 if y > n:
                     return x
                 x += 1



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