| Re: CASE statement [message #26938 is a reply to message #26552] |
Wed, 03 October 2001 23:51   |
R.Bauer
Messages: 1424
Registered: November 1998
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Senior Member |
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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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