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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/64497] std::scalbln does not round correctly for long doubles
Date: Mon, 05 Jan 2015 14:07:00 -0000	[thread overview]
Message-ID: <bug-64497-4-JNE7QsKxCi@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-64497-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64497

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Walter Mascarenhas from comment #2)
> What if there is a difference in the expected behavior
> for this function in  C and C++11?

There isn't any difference, so it doesn't matter.

> Is it not up to g++
> for implementing what is mandated in C++11? (This
> is not a rhetorical question, I really do not know the answer.)

Yes.

> On the other hand,
> http://en.cppreference.com/w/cpp/numeric/math/scalbn states that
> 
> "If a range error due to underflow occurs, the correct result (after
> rounding) is returned."

The C++ standard doesn't say that.

> I looked at the standard (N3797.pdf) but did not find anything
> specific about std::scalbln.

It says it is the same as C, so cppreference.com is wrong.


  parent reply	other threads:[~2015-01-05 14:07 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-05 10:40 [Bug c++/64497] New: " walter.mascarenhas at gmail dot com
2015-01-05 12:29 ` [Bug c++/64497] " redi at gcc dot gnu.org
2015-01-05 13:11 ` walter.mascarenhas at gmail dot com
2015-01-05 14:07 ` redi at gcc dot gnu.org [this message]
2015-01-05 14:13 ` redi at gcc dot gnu.org
2015-01-06  4:33 ` cubbi at cubbi dot org
2015-01-06  9:07 ` jakub at gcc dot gnu.org

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