Re: [bug-gawk] atan2(y,x) return value for y = 0 and x = -0

[Janis Papanagnou]

Complementary to Herman's view I think that -0 should be handled as +0;
so I'd qualify the first sample below as "Why is the result pi here?", and
the second sample as "Works as expected". Either way, I agree that this
looks like a bug.

Janis

> Date: Sat, 18 Jan 2014 14:56:19 +0100
> From: address@hidden
> To: address@hidden
> CC: address@hidden
> Subject: atan2(y,x) return value for y = 0 and x = -0
>
> Hi,
>
> This might be a feature or a bug, but I thought it would be worth reporting.
>
> # Works as expected
> $ awk 'BEGIN{ pi = atan2(0,-0) ; printf "%.16f\n", pi }'
> 3.1415926535897931
>
> # Why is the result 0 here ?
> $ awk -M 'BEGIN{ pi = atan2(0,-0) ; printf "%.16f\n", pi }'
> 0.0000000000000000
>
> # Works again as expected
> $ awk -M 'BEGIN{ pi = atan2(0,-0.1) ; printf "%.16f\n", pi }'
> 3.1415926535897931
>
> # I used gawk from git on Mac OS X, 10.9.1
> $ awk -V | head -1
> GNU Awk 4.1.60, API: 1.0 (GNU MPFR 3.1.1-p2, GNU MP 5.1.2)
>
> Hermann