Re: Absolute value of intervals

On Mon, Nov 02, 2009 at 10:52:40AM +0000, Jasen Betts wrote:
> what's the absolute value of '1month -30 days'::interval
>
> if I add it to the first of march it goes forwards if I add it to the
> first of february if goes backwards. if I add it to the first of april
> it goes nowhere.
>
> select '2008-02-01'::date + '1month -30days'::interval;
> select '2008-03-01'::date + '1month -30days'::interval;
> select '2008-04-01'::date + '1month -30days'::interval;
>
> I'm guessing that '1 month 30 days' is the only mathematically
> consistent answer, not that it's likely to be useful.

Except that this is not consistent with itself. Most definitions have
the absolute value of a number being the same as either the number
itself or its negation.

--
Sam http://samason.me.uk/