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Re: "1 + -1" when rounding to -inf
- From: Andreas Schwab <schwab at linux-m68k dot org>
- To: David Miller <davem at davemloft dot net>
- Cc: joseph at codesourcery dot com, libc-alpha at sourceware dot org
- Date: Mon, 21 Apr 2014 21:38:20 +0200
- 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> <20140421 dot 152406 dot 1095125135624062643 dot davem at davemloft dot net>
David Miller <davem@davemloft.net> writes:
> From: Andreas Schwab <schwab@linux-m68k.org>
> Date: Mon, 21 Apr 2014 21:22:07 +0200
>
>> David Miller <davem@davemloft.net> 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.
The log functions always return -inf for Â0, so does log1p(-1).
Andreas.
--
Andreas Schwab, schwab@linux-m68k.org
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