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Re: [Bug-gnulib] [RFC] Module: long double math functions

From: Paolo Bonzini
Subject: Re: [Bug-gnulib] [RFC] Module: long double math functions
Date: Tue, 11 Feb 2003 09:16:38 +0100
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>    sizeof (long double) > sizeof (double)

Not strictly necessary.  I.e. no infinite loops if sizeof (long double) == 
sizeof (double), only wasted time.

>    precisionof (long double) <= 2 * precisionof (double)

Not strictly necessary.  Results will not be precise to 1 ulp if the precision 
of long doubles is greater than 113 bits, though (are there such monsters?).

>    IEEE format

No.  That's the main change I made WRT glibc's code.

>    sizeof (long double) == 12 or == 16 ?


> If you have precision problems, you can look at the algorithms of
> Keith Briggs' doubledouble package (a.k.a. xdouble in LIDIA), see
> http://members.lycos.co.uk/keithmbriggs/doubledouble.html
> - his algorithms provide 106 bits of precision.

These also do, though they of course rely on the compiler being able to 
convert decimal constants properly.


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