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bpo-41421: Algebraic simplification for random.paretovariate() #21695

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rhettinger merged 2 commits into from
Aug 1, 2020
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bpo-41421: Algebraic simplification for random.paretovariate() #21695

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bpo-41421: Algebraic simplification for random.paretovariate()
rhettinger Jul 31, 2020
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rhettinger Aug 1, 2020
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2 changes: 1 addition & 1 deletion Lib/random.py
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Original file line number Diff line number Diff line change
Expand Up @@ -749,7 +749,7 @@ def paretovariate(self, alpha):
# Jain, pg. 495

u = 1.0 - self.random()
return 1.0 / u ** (1.0 / alpha)
return u ** (-1.0 / alpha)

def weibullvariate(self, alpha, beta):
"""Weibull distribution.
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3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Library/2020-08-01-00-51-15.bpo-41421.dHKRVB.rst
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@@ -0,0 +1,3 @@
Make an algebraic simplification to random.paretovariate(). It now is
slightly less subject to round-off error and is slightly faster. Inputs that
used to cause ZeroDivisionError now cause an OverflowError instead.