[New-bugs-announce] [issue40030] Error with math.fsum() regarding float-point error

[Mathias Talbo]

New submission from Mathias Talbo <mathiashoy at gmail.com>:

An issue occurs when running the following code. 

import math
math.fsum([0.1, 0.2]), math.fsum([0.1, 0.7])

This should output 0.3, 0.8 respectively.

Instead, it output 0.30000000000000004, 0.7999999999999999

The very floating-point error it is trying to stop from occurring.

Thank you for your time.

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components: Extension Modules
messages: 364730
nosy: Mathias Talbo
priority: normal
severity: normal
status: open
title: Error with math.fsum() regarding float-point error
type: behavior
versions: Python 3.8

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue40030>
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