Horton

Re: Greatest Common Divisor

Vik Fearing <vik.fearing@2ndquadrant.com>

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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>
Date: 2020-01-04T00:38:45Z
Lists: pgsql-hackers 
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

Commits

  1. Add functions gcd() and lcm() for integer and numeric types.