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From: "newbie-02 at gmx dot de" <sourceware-bugzilla@sourceware.org>
To: glibc-bugs@sourceware.org
Subject: [Bug math/31426] log10( 10^n ) poor accuracy in bin80 datatype, log10l( 1E+07l ) -> 7.000000000000000000434...
Date: Wed, 28 Feb 2024 12:49:38 +0000	[thread overview]
Message-ID: <bug-31426-131-58t9INgRPC@http.sourceware.org/bugzilla/> (raw)
In-Reply-To: <bug-31426-131@http.sourceware.org/bugzilla/>

https://sourceware.org/bugzilla/show_bug.cgi?id=31426

--- Comment #2 from b. <newbie-02 at gmx dot de> ---
@Andreas Schwab: 

thanks for the hint, it's 1 ULP off! 

add. observations: 
for 4933 positive integral powers of ten 
log10l has 1 ULP devia in 1730 cases, 
logl( 10^n ) / logl( 10 ) has 1 ULP devia in 486 cases, 
for 4950 negative integral powers of ten 
log10l has 1 ULP devia in 1745 cases, 
logl( 10^n ) / logl( 10 ) has 1 ULP devia in 501 cases, 
all these devias can be neutralized with simple recheck 
calculations, if! integral powers of ten are exact. #28474.

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      parent reply	other threads:[~2024-02-28 12:49 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-02-28 11:32 [Bug math/31426] New: " newbie-02 at gmx dot de
2024-02-28 11:49 ` [Bug math/31426] " schwab@linux-m68k.org
2024-02-28 12:49 ` newbie-02 at gmx dot de [this message]

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