gc_inout for multiple test points

From: Dave Allured - NOAA Affiliate <dave.allured_at_nyahnyahspammersnyahnyah>
Date: Wed Apr 03 2013 - 15:52:16 MDT

NCL team,

This is an enhancement request for the gc_inout function. The current
version in NCL 6.1.2 will test a single coordinate pair against one
polygon, in a single function call. But there is no direct way to
test an array of coordinate pairs against the same polygon. This
could be done with looping and many function calls, such as in
examples 4 and 5 on the shapefiles example page. Or one could make
many temporary copies of the test polygon with NCL conform methods,
and then use a single function call with its documented array method.

With increasing use of high resolution gridded data and high
resolution outline data, both of these existing iteration methods
become very taxing on CPU time and memory. Would it be possible to
enhance gc_inout so that if the third and fourth arguments are a
single polygon (i.e. one dimensional), then the first and second
arguments representing test points may be multidimensional, and the
same polygon test will be repeated over all test points? The function
result should then have the same dimensions as the first and second

It seems to me that array methods inside gc_inout should yield
significant speed improvements for large array tests. Thanks for your

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Received on Wed Apr 3 15:52:26 2013

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