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Re: i370 float.h values?
- From: "Ulrich Weigand" <Ulrich dot Weigand at de dot ibm dot com>
- To: Richard Henderson <rth at redhat dot com>
- Cc: gcc at gcc dot gnu dot org
- Date: Tue, 3 Sep 2002 15:15:28 +0200
- Subject: Re: i370 float.h values?
- Sensitivity:
Richard Henderson wrote:
>#define __DBL_MAX_EXP__ 64
>#define __DBL_MAX__ 0x0.ffffffffffffffp256 // 1.15792089237316193817e+77
>#define __FLT_MAX_EXP__ 64
>#define __FLT_MAX__ 0x0.ffffffp256F // 1.15792082335569848633e+77
These look wrong to me; they were correct the first time.
We have a 7-bit characteristic, with an exponent bias of -64.
No characteristic value is reserved for any special meaning.
This means the exponent ranges from -64 to +63.
So we should have a maximum exponent of 63, and maxmium values
in the order of 2**252. (The PoP states the maximum value is
about 7.2e+75.)
Mit freundlichen Gruessen / Best Regards
Ulrich Weigand
--
Dr. Ulrich Weigand
Linux for S/390 Design & Development
IBM Deutschland Entwicklung GmbH, Schoenaicher Str. 220, 71032 Boeblingen
Phone: +49-7031/16-3727 --- Email: Ulrich.Weigand@de.ibm.com