| ATAN inconsistencies [message #17729] |
Fri, 12 November 1999 00:00  |
bowman
Messages: 121
Registered: September 1991
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Senior Member |
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Here's a platform dependency that took me quite a while to track down.
The SGI (IRIX) version of IDL returns 0.0 when you try to take the
arctan(0/0). The Alpha version (properly) returns a NaN.
Ken Bowman
IDL Version 5.1 (IRIX mipseb). Research Systems, Inc.
IDL> print, atan(0.0, 0.0)
0.00000
IDL Version 5.1 (OSF alpha). Research Systems, Inc.
IDL> print, atan(0.0, 0.0)
NaNQ
% Program caused arithmetic error: Floating illegal operand
--
Dr. Kenneth P. Bowman, Professor 409-862-4060
Department of Meteorology 409-862-4466 fax
Texas A&M University bowmanATcsrp.tamu.edu
College Station, TX 77843-3150 Replace AT with @
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| Re: ATAN inconsistencies [message #17857 is a reply to message #17729] |
Mon, 15 November 1999 00:00  |
Michael Werger
Messages: 34
Registered: May 1997
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Member |
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"Kenneth P. Bowman" wrote:
>
> Here's a platform dependency that took me quite a while to track down.
>
> The SGI (IRIX) version of IDL returns 0.0 when you try to take the
> arctan(0/0). The Alpha version (properly) returns a NaN.
>
> Ken Bowman
>
> IDL Version 5.1 (IRIX mipseb). Research Systems, Inc.
> IDL> print, atan(0.0, 0.0)
> 0.00000
>
> IDL Version 5.1 (OSF alpha). Research Systems, Inc.
> IDL> print, atan(0.0, 0.0)
> NaNQ
> % Program caused arithmetic error: Floating illegal operand
IDL 5.2 on Solaris 2.7:
IDL> print, atan(0.0, 0.0)
0.00000
... Any comments about the proper handling? ;-)
--
Michael Werger ------------o
ESA ESTEC & Praesepe B.V. |
Astrophysics Division mwerger@astro.estec.esa.nl|
| Postbus 299 http://astro.estec.esa.nl |
| 2200 AG Noordwijk +31 71 565 3783 (Voice)
o------------------- The Netherlands +31 71 565 4690 (FAX)
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