Re: Proposal: Trigonometric functions in degrees

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Piotr Stefaniak <postgres(at)piotr-stefaniak(dot)me>
Cc: Noah Misch <noah(at)leadboat(dot)com>, Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, Peter Eisentraut <peter_e(at)gmx(dot)net>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Proposal: Trigonometric functions in degrees
Date: 2016-01-31 16:41:38
Views: Raw Message | Whole Thread | Download mbox | Resend email
Lists: pgsql-hackers

Piotr Stefaniak <postgres(at)piotr-stefaniak(dot)me> writes:
> These changes from 65abaab547a5758b0d6d92df4af1663bb47d545f
> - result = sign * cosd_q1(arg1) / sind_q1(arg1);
> + result = sign * ((cosd_q1(arg1) / sind_q1(arg1)) / cot_45);

> and

> - result = sign * sind_q1(arg1) / cosd_q1(arg1);
> + result = sign * ((sind_q1(arg1) / cosd_q1(arg1)) / tan_45);

> both introduce division by zero, don't they?

Huh? cot_45 and tan_45 are fixed values that should be very close to 1.
Or were you complaining that the potential div by 0 existed beforehand?

It's possible that we should check for sind_q1(arg1) or cosd_q1(arg1)
being zero before we try the divide, and substitute get_float8_infinity()
instead. But the regression tests exercise this case, and none of the
buildfarm members complained, so I'm a bit disinclined to add code for
that purpose. If anyone does report regression test failure here, we can
revisit the issue then.

regards, tom lane

In response to

Browse pgsql-hackers by date

  From Date Subject
Next Message Tom Lane 2016-01-31 16:50:04 Re: Fwd: Core dump with nested CREATE TEMP TABLE
Previous Message Noah Misch 2016-01-31 15:54:20 Re: Fwd: Core dump with nested CREATE TEMP TABLE