tags:

views:

394

answers:

3
Q: 

What is float('123.987') in Python?

It's 123.98699999999999 !

Why is that?

Thanks guys! :)

+14  A: 

See Why can't decimal numbers be represented exactly in binary

Plynx  2010-04-03 22:51:57
+6  A: 

The Python FAQ and tutorial address this issue pretty well, I think. More generally, both are excellent resources, well worth your time to browse if you have any interest in Python!-)

Alex Martelli  2010-04-03 23:02:01
that was very useful thanks!
RadiantHex  2010-04-04 00:15:19
+2  A: 

This has changed in/since Python 3.1.

See also: issue 1580

To your (already deleted) addition: Use the decimal package.

Debilski  2010-04-03 23:07:05
The conversion of float to string has changed, but not the conversion from string to float.
dan04  2010-04-03 23:20:18
@dan04: What do you mean? `float('0.2') == float(0.2)`
Debilski  2010-04-03 23:26:05
@Debilski: `repr(0.2)` used to be `'0.20000000000000001'`. Now it's just `'0.2'`.
dan04  2010-05-01 08:29:33

related questions

Programmatically talking to a Serial Port in OS X or Linux
Best ways to teach a beginner to program?
Calling a Function From a String With the Function's Name in Python
An executable Python app
Text Editor For Linux (Besides Vi)?
What Hosting Service is best for Django applications?
File size differences after copying a file to a server vía FTP
Python: what is the difference between (1,2,3) and [1,2,3], and when should I use each?
Python: What OS am I running on?
How do I make a menu in python that does not require the user to press (enter) to make a selection?
How do you express binary literals in Python?
What is the most efficient graph data structure in Python?
Adding a Method to an Existing Object
How to learn Python: Good Example Code?
How do I use Python's itertools.groupby()?
Python and MySQL
Class views in Django
Is there an IDE that provides code completion for Python
Using 'in' to match an attribute of Python objects in an array
cx_Oracle - what is the best way to iterate over a result set?
cx_Oracle - How do I access Oracle from Python?
Continuous Integration System for a Python Codebase
Get a preview jpeg of a pdf on windows?
How can I find the full path to a font from its display name on a Mac?
XML Processing in Python