| Re: CASE statement [message #27051 is a reply to message #26938] |
Fri, 05 October 2001 11:44   |
weitkamp
Messages: 33
Registered: October 1998
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Member |
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Reimar,
May I summarize the first statement you make like this: "KEYWORD_SET
is a nice function, but has the wrong name"?
It actually also has some counterintuitive features. This one, for
example:
IDL> PRINT, KEYWORD_SET([0])
1
The online help describes this behavior correctly, but accidentally
passing a 1-element array instead of a scalar happens easily. Wasn't
there something here recently about the pitfalls of IDL making a
difference between scalars and single-element arrays?
Timm
Timm Weitkamp
European Synchrotron Radiation Facility (ESRF), Grenoble, France
Phone: +33 4 76 88 28 86 E-mail: weitkamp@esrf.fr
Reimar Bauer <r.bauer@fz-juelich.de> wrote in message news:<3BBC0706.B983FB42@fz-juelich.de>...
> David Fanning wrote:
>>
>> George McCabe (george.mccabe@gsfc.nasa.gov) writes:
>>
>>> ;+
>>> ; PURPOSE:
>>> ; "On or Off", turn any variable into a strict logical type
>>> ; with only two values 0 or 1
>>> ;
>>
>> Impressive code, George. But couldn't this be
>> more simply done with this:
>>
>> on_off = Keyword_Set(variable)
>>
>
>
> Hi David and all others,
>
>
> the most problem with all these functions arg_present, n_elements,
> keyword_set
> is that's most beginners believe that's some of them only works by
> keywords
> and some only for positional parameters.
>
> To learn something about IDL and its parameters here are two exercises
> of our course.
>
>
> regards
>
> Reimar
>
>
> 1)
> There are three functions given
>
>
>
> FUNCTION test1,minimum=min_val
> IF KEYWORD_SET(min_val) THEN RETURN,1 ELSE RETURN,0
> END
>
>
> FUNCTION test2,minimum=min_val
> IF ARG_PRESENT(min_val) THEN RETURN,1 ELSE RETURN,0
> END
>
>
> FUNCTION test3,minimum=min_val
> IF N_ELEMENTS(min_val) GT 0 THEN RETURN,1 ELSE RETURN,0
> END
>
> Fill out the form:
>
>
>
>
> CALL | test1 | test2 |test3
> ____________________________________________________________ ____
> PRINT, testX( ) | | |
> ____________________________________________________________ ____
> PRINT, testX(minimum=0) | | |
> ____________________________________________________________ ____
> PRINT, testX(minimum=10) | | |
> ____________________________________________________________ ____
> PRINT, testX(minimum=-10) | | |
> ____________________________________________________________ ____
> mv=0 & PRINT, testX(minimum=mv) | | |
> ____________________________________________________________ _____
> mv=10 & PRINT, testX(minimum=mv) | | |
> ____________________________________________________________ _____
> PRINT, testX(minimum=mv2) | | |
> ____________________________________________________________ _____
>
>
>
>
>
> 2)
> There are three functions given
>
>
>
> FUNCTION test1,min_val
> IF KEYWORD_SET(min_val) THEN RETURN,1 ELSE RETURN,0
> END
>
>
> FUNCTION test2,min_val
> IF ARG_PRESENT(min_val) THEN RETURN,1 ELSE RETURN,0
> END
>
>
> FUNCTION test3,min_val
> IF N_ELEMENTS(min_val) GT 0 THEN RETURN,1 ELSE RETURN,0
> END
>
> Fill out the form:
>
>
>
>
> CALL | test1 | test2 |test3
> ____________________________________________________________ ____
> PRINT, testX( ) | | |
> ____________________________________________________________ ____
> PRINT, testX(0) | | |
> ____________________________________________________________ _____
> PRINT, testX(10) | | |
> ____________________________________________________________ ____
> PRINT, testX(-10) | | |
> ____________________________________________________________ ____
> mv=0 & PRINT, testX(mv) | | |
> ____________________________________________________________ _____
> mv=10 & PRINT, testX(mv) | | |
> ____________________________________________________________ _____
> PRINT, testX(mv2) | | |
> ____________________________________________________________ _____
>
>
>
> --
> Reimar Bauer
>
> Institut fuer Stratosphaerische Chemie (ICG-1)
> Forschungszentrum Juelich
> email: R.Bauer@fz-juelich.de
> http://www.fz-juelich.de/icg/icg1/
> ============================================================ ======
> a IDL library at ForschungsZentrum Juelich
> http://www.fz-juelich.de/icg/icg1/idl_icglib/idl_lib_intro.h tml
>
> http://www.fz-juelich.de/zb/text/publikation/juel3786.html
> ============================================================ ======
>
> read something about linux / windows
> http://www.suse.de/de/news/hotnews/MS.html
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