summaryrefslogtreecommitdiffstats
path: root/Lib/random.py
diff options
context:
space:
mode:
Diffstat (limited to 'Lib/random.py')
-rw-r--r--Lib/random.py11
1 files changed, 6 insertions, 5 deletions
diff --git a/Lib/random.py b/Lib/random.py
index ebab1f8..49921cb 100644
--- a/Lib/random.py
+++ b/Lib/random.py
@@ -182,12 +182,13 @@ def gauss(mu, sigma):
# When x and y are two variables from [0, 1), uniformly
# distributed, then
#
- # cos(2*pi*x)*log(1-y)
- # sin(2*pi*x)*log(1-y)
+ # cos(2*pi*x)*sqrt(-2*log(1-y))
+ # sin(2*pi*x)*sqrt(-2*log(1-y))
#
# are two *independent* variables with normal distribution
# (mu = 0, sigma = 1).
# (Lambert Meertens)
+ # (corrected version; bug discovered by Mike Miller, fixed by LM)
global gauss_next
@@ -196,9 +197,9 @@ def gauss(mu, sigma):
gauss_next = None
else:
x2pi = random() * TWOPI
- log1_y = log(1.0 - random())
- z = cos(x2pi) * log1_y
- gauss_next = sin(x2pi) * log1_y
+ g2rad = sqrt(-2.0 * log(1.0 - random()))
+ z = cos(x2pi) * g2rad
+ gauss_next = sin(x2pi) * g2rad
return mu + z*sigma