From: "Paul D. DeRocco" <pderocco@ix.netcom.com>
To: "eCos Discuss" <ecos-discuss@ecos.sourceware.org>
Subject: RE: [ECOS] One question.
Date: Wed, 31 May 2006 06:28:00 -0000 [thread overview]
Message-ID: <NEBBKHCFDGIGIJEHDJFCGEKHEIAB.pderocco@ix.netcom.com> (raw)
In-Reply-To: <F7DDB0A5340F2D47966F7AD8DF5447E3013427DD@INC-MX8.inc.iac>
> From: Zhao.Green@inventec-inc.com
>
> I use the ecos package , and I found the double type question
> Double dnum1 = 1234567.1
> Double dnum2 = 1234567
> Double result = 0 ;
>
> Result = dnum1-dnum2 ;
>
> The result is 0.10000000009
>
> Anybody know how to solve this question?
0.1 can't be represented exactly in binary, so there's an inevitable
roundoff error. Sometimes these errors are hidden by the implementation of
the binary to decimal conversion used in printing out the answer, but
sometimes not. I don't know if you're using printf in C, or << in C++, but
you might try requesting less precision in the output, to see if that rounds
the result back to 0.1.
--
Ciao, Paul D. DeRocco
Paul mailto:pderocco@ix.netcom.com
--
Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos
and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss
next prev parent reply other threads:[~2006-05-31 6:28 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-31 5:15 Zhao.Green
2006-05-31 6:12 ` Fabian Scheler
2006-05-31 6:28 ` Paul D. DeRocco [this message]
-- strict thread matches above, loose matches on Subject: below --
2006-05-31 6:50 Zhao.Green
2006-05-31 7:58 ` Michele Portolan
2006-05-31 11:49 ` Edgar Grimberg
2004-06-25 8:09 anton yakovlev
2004-06-25 11:28 ` Gary Thomas
2004-06-26 8:59 ` anton yakovlev
2004-06-26 11:50 ` Gary Thomas
2004-06-26 12:26 ` anton yakovlev
2004-06-26 12:31 ` Gary Thomas
2004-06-26 15:40 ` anton yakovlev
[not found] ` <40DBE222.8040603@codito.com>
2004-06-26 8:49 ` anton yakovlev
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