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Re: Problem with double precision in g77

From: James E Wilson <wilson at specifixinc dot com>
To: ew fgff <sah_8 at yahoo dot com>
Cc: gcc-bugs at gcc dot gnu dot org
Date: Thu, 12 Aug 2004 19:54:17 -0700
Subject: Re: Problem with double precision in g77
References: <20040810152423.18110.qmail@web52701.mail.yahoo.com>

ew fgff wrote:

         if(a .eq. p)then
           print*,a
         endif

Exact comparison of FP values often doesn't work because of rounding errors.

None of the values 0.1, 0.2, or 0.3 can be exactly represented in the binary FP double format. They are all rounded approximations. When you add 0.1 to 0.2, you get another rounded approximation, which is different than the other rounded approximation you got for 0.3. -- Jim Wilson, GNU Tools Support, http://www.SpecifixInc.com

References:
- Problem with double precision in g77
  - From: ew fgff

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