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Date: Tue, 06 Oct 2009 15:03:59 -0500
From: Eric Rudd <rudd AT cyberoptics DOT com>
Organization: CyberOptics
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To: djgpp-workers AT delorie DOT com
Subject: Re: atan2 bug
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Reply-To: djgpp-workers AT delorie DOT com

Juan Manuel Guerrero wrote:
> -	jnz	badarg
> -	movl	4(%esp), %eax
> +	jne	badarg			/* x = NaN */
> +	movl	12(%esp), %eax

I wrote this routine many years ago, so I thought I would be in a good 
position to examine the proposed changes.  When I ran the original code 
for atan2(3, +inf), it actually produced the correct answer, but after 
inspecting the code, I see that there actually *is* a bug, and that the 
correct result I got was because the value at 4(%esp) just happened to 
be zero on my platform.  I agree with the changes proposed.

Unfortunately, if we want the code to conform to C99, most of these 
exception tests should be removed.

-Eric Rudd