New submission from Raymond Hettinger <[email protected]>:
Consider adding new non-sequence fields to sys.float_info: doubling_rounding
and ieee_754.
The code in test_math defines a useful constant:
# detect evidence of double-rounding: fsum is not always correctly
# rounded on machines that suffer from double rounding.
x, y = 1e16, 2.9999 # use temporary values to defeat peephole optimizer
HAVE_DOUBLE_ROUNDING = (x + y == 1e16 + 4)
There is another useful value in a float.__getformat__ which is hard to find
and only documented for internal use:
>>> float.__getformat__('double')
'IEEE, little-endian
Making this information available would make it easier for users to do what we
do in test_math:
@requires_IEEE_754
@unittest.skipIf(HAVE_DOUBLE_ROUNDING,
"fsum is not exact on machines with double rounding")
def testFsum(self):
...
----------
components: Extension Modules
messages: 377237
nosy: mark.dickinson, rhettinger, tim.peters
priority: normal
severity: normal
status: open
title: Add more fields to sys.float_info
versions: Python 3.10
_______________________________________
Python tracker <[email protected]>
<https://bugs.python.org/issue41823>
_______________________________________
_______________________________________________
Python-bugs-list mailing list
Unsubscribe:
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
