Re: Atan2 and angle between vectors

[Alexandre Rion <gaumerie@...>]

To calculate the angle beteween the two vectors, you sould do:

math.atan2(b[2],b[1]) - math.atan2(a[2],a[1])


Alexandre

-----Message d'origine----- 
From: Miles Bader 
Sent: Tuesday, April 03, 2012 6:40 AM 
To: Rena 
Cc: Lua mailing list 
Subject: Re: Atan2 and angle between vectors 

Rena <hyperhacker@gmail.com> writes:
> I just discovered that math.atan2 doesn't handle the case of y=0
> properly, at least in Lua 5.1:
>
> > a, b = {-1, 0}, {1, 0}
> > =math.deg(math.atan2(b[2] - a[2], b[1] - a[1]))
> 0

That is the correct result.

Anyway, Lua's atan2 just calls the C library's atan2, so if you notice
any problem, it's more likely to be with the C library.

-Miles

--
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