From: Paolo Carlini <pcarlini@suse.de>
To: Michael Veksler <VEKSLER@il.ibm.com>
Cc: gcc@gcc.gnu.org
Subject: Re: tr1::unordered_set<double> bizarre rounding behavior (x86)
Date: Tue, 05 Jul 2005 17:04:00 -0000 [thread overview]
Message-ID: <42CABDCC.3070508@suse.de> (raw)
In-Reply-To: <OF340AFDFE.4774C997-ON43257035.003F59A4-43257035.0047DBFD@il.ibm.com>
Michael Veksler wrote:
> std::tr1::hash<dobule> is implemented in a very bad way.
> it casts double to size_t, which of course does a very poor job on big
> values (is the result of 1.0e100 cast to size_t defined ?).
>
>
A possible solution would be using frexp & co to extract the mantissa
and then work on it, one way or the other. You can find it proposed
around. Then, often the exponent is simply discarded.
What do you think?
In case, please add your comments to the audit trail of 21193. I mean to
work pretty soon on improving those hash functions.
Paolo.
next prev parent reply other threads:[~2005-07-05 17:04 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-07-05 13:05 Michael Veksler
2005-07-05 13:32 ` Paolo Carlini
2005-07-05 15:43 ` Michael Veksler
2005-07-05 15:57 ` Gabriel Dos Reis
2005-07-05 16:04 ` Paolo Carlini
2005-07-05 20:18 ` Michael Veksler
2005-07-05 20:22 ` Paolo Carlini
2005-07-05 20:36 ` Michael Veksler
2005-07-05 20:41 ` Paolo Carlini
2005-07-05 20:47 ` Paolo Carlini
2005-07-05 21:12 ` Michael Veksler
2005-07-05 21:21 ` Gabriel Dos Reis
2005-07-05 14:28 ` Gabriel Dos Reis
2005-07-05 17:04 ` Paolo Carlini [this message]
2005-07-05 18:06 ` Gabriel Dos Reis
2005-07-05 18:10 ` Joe Buck
2005-07-05 18:32 ` Gabriel Dos Reis
2005-07-05 18:42 ` Paolo Carlini
2005-07-05 19:18 ` Gabriel Dos Reis
2005-07-05 19:52 ` Paolo Carlini
2005-07-05 20:24 ` Gabriel Dos Reis
2005-07-05 19:01 ` Michael Veksler
2005-07-05 19:24 ` Gabriel Dos Reis
2005-07-06 12:38 ` Avi Kivity
2005-07-06 12:54 ` Gabriel Dos Reis
2005-07-06 12:54 ` Michael Veksler
2005-07-06 13:01 ` Avi Kivity
2005-07-06 13:50 ` Gabriel Dos Reis
2005-07-05 18:08 ` Joe Buck
2005-07-05 18:12 ` Paolo Carlini
2005-07-05 19:58 ` Joe Buck
2005-07-05 19:59 ` Paolo Carlini
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