[ python-Bugs-1478429 ] datetime.datetime.fromtimestamp ValueError. Rounding error

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Bugs item #1478429, was opened at 2006-04-28 14:37
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Category: Python Library
Group: Python 2.4
Status: Open
Resolution: None
Priority: 5
Submitted By: Erwin Bonsma (eriban)
Assigned to: Nobody/Anonymous (nobody)
Summary: datetime.datetime.fromtimestamp ValueError. Rounding error

Initial Comment:
The function datetime.datetime.fromtimestamp() can 
throw a ValueError when the timestamp is close to an 
integer value but not quite due to rounding errors. It 
then gives the following error: microsecond must be in 
0..999999

This can be seen by running the attached code (the 
values are taken from an actual event log), which 
gives the following output:


1146227423.0 -> 2006-04-28 14:30:23
1146227448.7 -> 2006-04-28 14:30:48.702000
1146227459.95 -> 2006-04-28 14:30:59.947000
1146227468.41 -> 2006-04-28 14:31:08.409000
1146227501.4 -> 2006-04-28 14:31:41.399000
1146227523.0 -> Error converting 1146227522.99999976
microsecond must be in 0..999999


Admittedly, I can work around the bug in this case, by 
summing the durations first, and calculating all times 
from "starttime" directly. Nevertheless, I think this 
is a bug in datetime, as it should work as long as the 
input time any floating point value within a given 
range (based on the date range that is supported).

Details of my Python environment:
Python 2.4.2 (#1, Feb  6 2006, 13:53:18) 
[GCC 3.2.3 20030502 (Red Hat Linux 3.2.3-53)] on linux2


Cheers,

Erwin

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