From: Dima Volodin <dvv@dvv.ru>
To: Sam Lantinga <slouken@devolution.com>
Cc: egcs@egcs.cygnus.com, highlander@lokigames.com, dvenckus@activision.com
Subject: Re: Rounding errors using doubles?
Date: Thu, 18 Mar 1999 16:54:00 -0000 [thread overview]
Message-ID: <36F1A032.75E4DD44@dvv.ru> (raw)
In-Reply-To: <E10NnPU-0006Cc-00@roboto.devolution.com>
Sam Lantinga wrote:
> I have to thank everyone here on this list for your responsiveness.
> The problem was caused by unexpected values in code using doubles
> that was ported from Windows. Apparently, by default, Windows uses
> 53 bits of precision for it's double operations. Linux uses 64 bits.
>
> Since the code relies on the exact behavior of doubles quite extensively,
> we are setting the precision of the FPU to 53 bits using the fldcw
> instruction. :)
>
> BTW, does anyone know what precision is used on the PPC and Alpha
> architectures?
Man, I'm telling you - your code is _broken_. It's just sheer luck you see it
working at all.
> -Sam Lantinga (slouken@devolution.com)
Dima
WARNING: multiple messages have this Message-ID
From: Dima Volodin <dvv@dvv.ru>
To: Sam Lantinga <slouken@devolution.com>
Cc: egcs@egcs.cygnus.com, highlander@lokigames.com, dvenckus@activision.com
Subject: Re: Rounding errors using doubles?
Date: Wed, 31 Mar 1999 23:46:00 -0000 [thread overview]
Message-ID: <36F1A032.75E4DD44@dvv.ru> (raw)
Message-ID: <19990331234600.fANCq0C_XfEQF-9GJWEa0HOMN-NogCgdsdwE9fKfW_g@z> (raw)
In-Reply-To: <E10NnPU-0006Cc-00@roboto.devolution.com>
Sam Lantinga wrote:
> I have to thank everyone here on this list for your responsiveness.
> The problem was caused by unexpected values in code using doubles
> that was ported from Windows. Apparently, by default, Windows uses
> 53 bits of precision for it's double operations. Linux uses 64 bits.
>
> Since the code relies on the exact behavior of doubles quite extensively,
> we are setting the precision of the FPU to 53 bits using the fldcw
> instruction. :)
>
> BTW, does anyone know what precision is used on the PPC and Alpha
> architectures?
Man, I'm telling you - your code is _broken_. It's just sheer luck you see it
working at all.
> -Sam Lantinga (slouken@devolution.com)
Dima
next prev parent reply other threads:[~1999-03-18 16:54 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-03-18 16:45 Sam Lantinga
1999-03-18 16:54 ` Dima Volodin [this message]
1999-03-31 23:46 ` Dima Volodin
[not found] ` < E10NnPU-0006Cc-00@roboto.devolution.com >
1999-03-18 16:57 ` David Edelsohn
1999-03-31 23:46 ` David Edelsohn
1999-03-31 23:46 ` Sam Lantinga
-- strict thread matches above, loose matches on Subject: below --
1999-03-19 9:08 Sam Lantinga
[not found] ` < E10O2lP-0006t2-00@roboto.devolution.com >
1999-03-19 9:43 ` craig
1999-03-31 23:46 ` craig
1999-03-31 23:46 ` Sam Lantinga
1999-03-18 17:43 Ross Smith
[not found] ` < 002d01be71aa$30d420e0$a8a11dcb@animal.ihug.co.nz >
1999-03-19 6:36 ` craig
[not found] ` < 19990319142042.16973.qmail@deer >
1999-03-19 6:36 ` craig
1999-03-31 23:46 ` craig
1999-03-31 23:46 ` craig
1999-03-31 23:46 ` Ross Smith
1999-03-18 15:41 Sam Lantinga
[not found] ` < E10NmPs-0005mx-00@roboto.devolution.com >
1999-03-18 15:51 ` Sylvain Pion
1999-03-31 23:46 ` Sylvain Pion
1999-03-18 16:12 ` Joe Buck
[not found] ` < 199903190011.QAA11085@atrus.synopsys.com >
1999-03-18 16:25 ` Joe Buck
1999-03-31 23:46 ` Joe Buck
1999-03-31 23:46 ` Joe Buck
1999-03-18 15:54 ` Dima Volodin
1999-03-31 23:46 ` Dima Volodin
1999-03-31 23:46 ` Sam Lantinga
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