Message 167309 - Python tracker

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In-reply-to
Author	mark.dickinson
Recipients	mark.dickinson, skrah, steven.daprano
Date	2012年08月03日.12:06:44
SpamBayes Score	-1.0
Marked as misclassified	Yes
Message-id	<1343995605.27.0.275832929857.issue15544@psf.upfronthosting.co.za>

Content
> Decimal('snan').is_nan() > just returns true and I am under the impression that IEEE 754 specifies > the same. Sure, but IEEE 754 also specifies that math.sqrt(<signalling nan>) should signal. Since both math.sqrt and math.isnan are going through __float__, we can't keep everyone happy here. The question for me is really what __float__ should do. IEEE 754 doesn't help here, since it doesn't cover decimal floating-point <-> binary floating-point conversions.

Content

> Decimal('snan').is_nan()
> just returns true and I am under the impression that IEEE 754 specifies > the same.
Sure, but IEEE 754 also specifies that math.sqrt(<signalling nan>) should signal. Since both math.sqrt and math.isnan are going through __float__, we can't keep everyone happy here.
The question for me is really what __float__ should do. IEEE 754 doesn't help here, since it doesn't cover decimal floating-point <-> binary floating-point conversions.

History
Date	User	Action	Args
2012年08月03日 12:06:45	mark.dickinson	set	recipients: + mark.dickinson, steven.daprano, skrah
2012年08月03日 12:06:45	mark.dickinson	set	messageid: <1343995605.27.0.275832929857.issue15544@psf.upfronthosting.co.za>
2012年08月03日 12:06:44	mark.dickinson	link	issue15544 messages
2012年08月03日 12:06:44	mark.dickinson	create

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