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Re: ATAN function with two ARGS [message #20279]

Tue, 06 June 2000 00:00

K. Bowman
Messages: 330
Registered: May 2000

Senior Member

In article <MPG.13a582048e3c14e9989b49@news.frii.com>, David Fanning
<davidf@dfanning.com> wrote:

> Ben Tupper (tupper@seadas.bigelow.org) writes:
>
>> If this argument is supplied, ATAN returns the angle whose tangent
>> is equal to Y/X. If both arguments are zero, the result is undefined.
>
> Notice they don't say the "result of the function" is
> undefined. If they did, I could understand your confusion.
> But here they have made a truthful and accurate statement.
> *Implying* that they were talking about the result of the
> function is an old technical writers trick that allows one
> to remain truthful, while still confusing the rift-raft.

The result of ATAN(0.0,0.0) in IDL is implementation dependent, viz.

Logging into SGI IRIX
IDL Version 5.3 (IRIX mipseb). (c) 1999, Research Systems, Inc.
IDL> print, atan(0.0, 0.0)
0.00000

Logging into DEC Unix
IDL Version 5.3 (OSF alpha). (c) 1999, Research Systems, Inc.
IDL> print, atan(0.0, 0.0)
-NaN

In some cases it really is undefined. ;-)

Ken
One of the riff-raff (i.e., those people or that segment of society
regarded as worthless, disreputable, insignificant, etc.; rabble)

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[Message index]

		Re: ATAN function with two ARGS By: K. Bowman on Tue, 06 June 2000 00:00
		Re: ATAN function with two ARGS By: Ben Tupper on Tue, 06 June 2000 00:00
		Re: ATAN function with two ARGS By: davidf on Mon, 05 June 2000 00:00
		Re: ATAN function with two ARGS By: Ben Tupper on Mon, 05 June 2000 00:00
		Re: ATAN function with two ARGS By: Ben Tupper on Mon, 05 June 2000 00:00
		Re: ATAN function with two ARGS By: davidf on Mon, 05 June 2000 00:00

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