Subject: Re: Greatest Common Divisor
To: Fabien COELHO <coelho@cri.ensmp.fr>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, 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>
 <alpine.DEB.2.21.1912281848540.24861@pseudo>
 <dbf86808-91fa-3262-f939-2ef3d38ec242@2ndquadrant.com>
 <alpine.DEB.2.21.1912290815520.889@pseudo>
 <5E08D947.9000902@anastigmatix.net>
 <alpine.DEB.2.21.1912291755510.14206@pseudo>
 <CAEZATCX9YgkWupVFcJ5ixkEJMyf2X5ZecN8K5r12oOB8mDHzWQ@mail.gmail.com>
 <20200102145712.GN3195@tamriel.snowman.net> <16242.1577977961@sss.pgh.pa.us>
 <6855727c-3836-21cc-18f9-e79227b99079@2ndquadrant.com>
 <alpine.DEB.2.21.2001032010470.12030@pseudo>
 <5bf72c6b-1290-2ba0-770b-8a13e899fd98@2ndquadrant.com>
 <alpine.DEB.2.21.2001040925230.31333@pseudo>
From: Vik Fearing <vik.fearing@2ndquadrant.com>
Message-ID: <4998d2c6-ba16-e6eb-df0c-e5fbf234d52d@2ndquadrant.com>
Date: Sat, 4 Jan 2020 10:30:55 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.2.2
MIME-Version: 1.0
In-Reply-To: <alpine.DEB.2.21.2001040925230.31333@pseudo>
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit
Content-Language: en-US
Precedence: bulk

On 04/01/2020 09:35, 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?
>
> ISTM that the current implementation has:
>
>   \forall int4 n, n \neq MIN_INT4, \gcd(n, 0) = 0 ?
>
> In which case applying the same rule for min int seems ok. 


No, gcd(n, 0) = n.

-- 

Vik Fearing