** operator yielding wrong result for negative numbers

[eswars]

BPO	10061
Nosy	@rhettinger, @orsenthil

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

Show more details

GitHub fields:

assignee = None
closed_at = <Date 2010-10-10.06:49:33.761>
created_at = <Date 2010-10-10.06:41:19.382>
labels = ['build', 'invalid']
title = '** operator yielding wrong result for negative numbers'
updated_at = <Date 2010-10-10.19:23:42.003>
user = 'https://bugs.python.org/eswars'

bugs.python.org fields:

activity = <Date 2010-10-10.19:23:42.003>
actor = 'rhettinger'
assignee = 'none'
closed = True
closed_date = <Date 2010-10-10.06:49:33.761>
closer = 'orsenthil'
components = ['None']
creation = <Date 2010-10-10.06:41:19.382>
creator = 'eswar.s'
dependencies = []
files = []
hgrepos = []
issue_num = 10061
keywords = []
message_count = 3.0
messages = ['118311', '118313', '118342']
nosy_count = 3.0
nosy_names = ['rhettinger', 'orsenthil', 'eswar.s']
pr_nums = []
priority = 'normal'
resolution = 'not a bug'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'compile error'
url = 'https://bugs.python.org/issue10061'
versions = ['Python 2.6']

[eswars]

-5 ** 4 results as -625. It should be 625

[orsenthil]

It's to do with operator precedence.
** takes higher precedence than negative.

http://docs.python.org/reference/expressions.html#Summary

(-5) ** 4 will give what you are looking for.

[rhettinger]

Python's order of operations runs the exponentation before the unary minus. This convention makes the unary minus behave more like the subtraction operator so that: -x**n == 0 - x**n.

This convention is somewhat common but there are exceptions such as MS Excel where the unary minus binds first. See http://en.wikipedia.org/wiki/Order_of_operations#Examples