Subject: Re: Greatest Common Divisor
From: Vik Fearing <vik.fearing@2ndquadrant.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Fabien COELHO <coelho@cri.ensmp.fr>, Stephen Frost <sfrost@snowman.net>,
 Dean Rasheed <dean.a.rasheed@gmail.com>,
 Chapman Flack <chap@anastigmatix.net>,
 PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
References: <adbd3e0b-e3f1-5bbc-21db-03caf1cef0f7@2ndquadrant.com>
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 <CAEZATCX9YgkWupVFcJ5ixkEJMyf2X5ZecN8K5r12oOB8mDHzWQ@mail.gmail.com>
 <20200102145712.GN3195@tamriel.snowman.net> <16242.1577977961@sss.pgh.pa.us>
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Message-ID: <0d4d936c-a409-e609-d0fd-2e009b2f47e1@2ndquadrant.com>
Date: Sat, 4 Jan 2020 01:38:45 +0100
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On 04/01/2020 01:26, Vik Fearing wrote:
> On 04/01/2020 01:21, Tom Lane wrote:
>> Vik Fearing <vik.fearing@2ndquadrant.com> writes:
>>> On 03/01/2020 20:14, Fabien COELHO wrote:
>>>> I'm unsure about gcd(INT_MIN, 0) should error. Possibly 0 would be nicer?
>>> What justification for that do you have?
>> Zero is the "correct" answer for that, isn't it, independently of overflow
>> considerations?  
>
> I would say not.  The correct answer is INT_MIN but we've decided a
> negative result is not desirable.


Wolfram Alpha agrees.

https://www.wolframalpha.com/input/?i=gcd%28-9223372036854775808%2C0%29

-- 

Vik Fearing