Re: [PATCH] Improve geometric types

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>
Cc: emre(at)hasegeli(dot)com, Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>, Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: [PATCH] Improve geometric types
Date: 2018-09-26 20:58:14
Message-ID: 12821.1537995494@sss.pgh.pa.us
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Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com> writes:
> Hmmm, interesting. It seems both failures happen in the chunk that
> multiplies paths with points, i.e. essentially point_mul_point. So it
> seems most platforms end up with

> (0,0) * (-3,4) = (-0, 0)

> while gaur apparently thinks it's (0,0). And indeed, that's what the
> attached trivial program does - I'd bet if you run it on gaur, it'll
> print 0.000000, not -0.000000.

Nope, no cigar:

$ gcc -Wall -O2 test.c
$ ./a.out
-0.000000

(I tried a couple other -O levels to see if that affected anything,
but it didn't.)

I'll try to isolate the problem more closely, but it will take awhile.
That machine is slow :-(

regards, tom lane

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