[Issue 1877] Errors in the documentation of std.math.atan2

[Bill Baxter]

d-bugmail at puremagic.com wrote:
> http://d.puremagic.com/issues/show_bug.cgi?id=1877
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> ------- Comment #1 from clugdbug at yahoo.com.au  2008-02-29 02:15 -------
> (In reply to comment #0)
>> First of all, the doc states "Calculates the arc tangent of y / x, returning a
>> value ranging from -π/2 to π/2." which should be "..from -π to π.", as is
>> shown in the table.
>>
>> Then, there are a couple of inconsistencies in the "Special Values" table:
>> "±0.0 ±0.0 ±0.0" should be "±0.0 +0.0 ±0.0",
>> "<0.0 ±0.0 π/2" should be "<0.0 ±0.0 -π/2",
>> ">0.0 ∞ ±0.0" should be "anything ∞ ±0.0",
>> ">0.0 -∞ ±π" should be "anything -∞ ±π".
>>
> 
> You're correct for the first three, but not for the last two. atan2(NaN, inf)
> is NaN, not +-0. Also atan2(inf, inf) is pi/4.

Who says the atan2(inf,inf) is pi/4?  Is that an IEEE thing?
Seems odd since that's like saying atan(inf/inf), and inf/inf is NaN, 
isn't it?
Put another way atan2(inf,inf)
the limit of any atan2(k*x,x) as x gets big.  Since k could be anything, 
it seems strange for the value to suddenly change to pi/4 when x becomes 
inf.

--bb