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Re: "1 + -1" when rounding to -inf
- From: David Miller <davem at davemloft dot net>
- To: schwab at linux-m68k dot org
- Cc: joseph at codesourcery dot com, libc-alpha at sourceware dot org
- Date: Mon, 21 Apr 2014 15:24:06 -0400 (EDT)
- Subject: Re: "1 + -1" when rounding to -inf
- Authentication-results: sourceware.org; auth=none
- References: <20140421 dot 145126 dot 1827736942397193476 dot davem at davemloft dot net> <87ioq2trmo dot fsf at igel dot home>
From: Andreas Schwab <email@example.com>
Date: Mon, 21 Apr 2014 21:22:07 +0200
> David Miller <firstname.lastname@example.org> writes:
>> I wrote a simple test program and, with FE_DOWNWARD, the sequence is:
>> -1 + 1 == -0.0L
>> -1L / -0.0L == INF
> Both are correct (the latter is independent of the rounding direction).
The test case is expecting -INF.
For all other rounding modes, for long double, log1p does return -INF.