Float Multiplication

[vktor]

BPO	816946
Nosy	@mwhudson, @freddrake

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

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GitHub fields:

assignee = 'https://github.com/freddrake'
closed_at = <Date 2003-10-06.10:07:42.000>
created_at = <Date 2003-10-03.04:09:06.000>
labels = ['invalid', 'docs']
title = 'Float Multiplication'
updated_at = <Date 2003-10-06.10:07:42.000>
user = 'https://bugs.python.org/vktor'

bugs.python.org fields:

activity = <Date 2003-10-06.10:07:42.000>
actor = 'mwh'
assignee = 'fdrake'
closed = True
closed_date = None
closer = None
components = ['Documentation']
creation = <Date 2003-10-03.04:09:06.000>
creator = 'vktor'
dependencies = []
files = []
hgrepos = []
issue_num = 816946
keywords = []
message_count = 5.0
messages = ['18523', '18524', '18525', '18526', '18527']
nosy_count = 4.0
nosy_names = ['mwh', 'fdrake', 'effbot', 'vktor']
pr_nums = []
priority = 'normal'
resolution = 'not a bug'
stage = None
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue816946'
versions = ['Python 2.3']

[vktor]

Why (1.16 * 100) is not the same than (1.16 * 10 * 10)?

I tried 1.16*100. also and it is = 115.99999999; but if I
do 1.16*10*10 I get 116.

Thanks....

[effbot]

Logged In: YES
user_id=38376

The answer to your question can be found in the Python
tutorial, and has nothing to do with regular expressions:

http://www.python.org/doc/tut/node14.html

Please don't use the bug tracker to ask for help in the
future; I suggest asking on comp.lang.python (for other
help forums, see www.python.org).

[vktor]

Logged In: YES
user_id=879316

I'sorry, but I don't agree...
Even 3.13 (3.1299999999999999) * 100 is 313 = like
3.13*10*10 (3.13*100=3.13*10*10)
In this case 1.16*100 <> 1.16*10*10
Sorry again, but it is a huge difference when you do int
(1.16*100)=115 or you do int(1.16*10*10)=116
Thanks...

[vktor]

Logged In: YES
user_id=879316

This is not a bug.

Binary floating point cannot represent decimal fractions exactly,
so some rounding always occurs (even in Python 1.5.2).

What changed is that Python 2.0 shows more precision than before
in certain circumstances (repr() and the interactive prompt).

You can use str() or print to get the old, rounded output:

>>> print 0.1+0.1
0.2
>>>

Follow the link for more information:

http://www.python.org/doc/2.2.1/tut/node14.html

[mwhudson]

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user_id=6656

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