| IDL map_set question [message #8907] |
Tue, 13 May 1997 00:00  |
Wayne Keith
Messages: 1
Registered: May 1997
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Junior Member |
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I am fairly new to IDL and am having trouble with the map_set function
making an orthographic projection. I can do the default, but in the
reference guide it says "If the keyword LIMIT is not set, the region of
the globe mapped to the UV plane is the hemisphere around the center of
the projection." I am doing a plot with the North pole centered and
would like to limit the plot at 30deg, but I can't figure out how to make
the LIMIT keyword work properly for this projection style. Folowing the
reference guide directions for LIMIT I keep getting floating point
errors. Can anyone help?
Wayne Keith
Rice University
(713) 527-8750 ext 3551
http://spacsun.rice.edu/~waynek
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Error message of the week: ...File not found. Should I fake it? (Y/N)
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| Re: IDL map_set question [message #8998 is a reply to message #8907] |
Wed, 14 May 1997 00:00  |
wmc
Messages: 117
Registered: February 1995
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Senior Member |
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In article ya023080001305971750250001@news.frii.com, davidf@dfanning.com (David Fanning) instructed:
> Wayne Keith <waynek@spacsun.rice.edu> enquired:
>> I am fairly new to IDL and am having trouble with the map_set function
>> making an orthographic projection.
>> Folowing the
>> reference guide directions for LIMIT I keep getting floating point
>> errors. Can anyone help?
> Polar orthographic? Auh, oh.
> I tried this and didn't get any errors:
> IDL> Map_Set, /Ortho, 90, 0, /Grid, /Cont, Limit=[30,-180, 90, 180], /Label
This works for me too (of course it does, it comes from DF ;-) You might
want to add /iso, too).
However, you problem with FP errors is familiar... I have a slight feeling
that is sometimes occurs when you get the SWNE the wrong way round in the
limit variable... but I can't reproduce it just now...
...Haha, yes I can. Actually it seems to occur if you make S and N
the same. Look:
wmc> Map_Set, /Ortho, 90, /Grid, /Cont, Limit=[80,30, 80, 90], /Label,/iso
% Program caused arithmetic error: Floating illegal operand
However, this is not a sensible thing to do...
- William
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