New submission from Mark Dickinson:
The following calculations should all be giving the same result:
>>> import statistics
>>> statistics.geometric_mean([2, 3, 5, 7])
3.80675409583932
>>> statistics.geometric_mean([2, 3, 5, 7.0])
1.6265765616977859
>>> statistics.geometric_mean([2, 3, 5.0, 7.0])
2.4322992790977875
>>> statistics.geometric_mean([2, 3.0, 5.0, 7.0])
3.201085872943679
>>> statistics.geometric_mean([2.0, 3.0, 5.0, 7.0])
3.80675409583932
(Correct result is 3.80675409583932.)
The culprit is this line in statistics._product:
mant, scale = 1, 0 #math.frexp(prod) # FIXME
... and indeed, we should be starting from `prod` rather than 1 here. But
simply using math.frexp has potential for failure if the accumulated integer
product overflows a float.
----------
assignee: steven.daprano
messages: 277808
nosy: mark.dickinson, steven.daprano
priority: normal
severity: normal
status: open
title: statistics.geometric_mean gives incorrect results for mixed int/float
inputs
type: behavior
versions: Python 3.6, Python 3.7
_______________________________________
Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue28327>
_______________________________________
_______________________________________________
Python-bugs-list mailing list
Unsubscribe:
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
