keyword issue (top 10 IDL request?)

[Kenneth Mankoff <mankoff(at)lasp.colorado.edu>]

Hi all,
   
here is another thing with current versions of IDL that causes problems
and confuses me:

a keyword set to 0 should not be undefined, it should be defined as zero.
For example:

IDL> create_globe, lat=90, long=0, ... 
I want create_globe to put longitude 0 at the center of the image (i.e.
pass "0" to map_set). But if i don't use long= at all, then it should be
undefined, and the following code should run (inside create_globe)
IF ( NOT KEYWORD_SET( long ) ) THEN long = 277.5  ;;; geomagnetic pole '98

However, the above line of code runs even if i set long to "0". I have
been using long=0.1 as a work-around, but this is an ugly hack that others
might not think to use.

any ideas to fix this are welcome, and if no one has any good ideas, then
please add this to your top ten list, David Fanning.


Thanks,
  ken.