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Date:         Wed, 2 Apr 1997 10:26:18 +0000
Reply-To:     "Keith J. Brown" <kjb@GA.UNC.EDU>
Sender:       "SAS(r) Discussion" <SAS-L@UGA.CC.UGA.EDU>
From:         "Keith J. Brown" <kjb@GA.UNC.EDU>
Organization: The University of North Carolina at Chapel Hill
Subject:      2 Mapping Questions
Content-Type: text/plain; charset=us-ascii

Hi all, I've got a couple of questions relating to mapping in SAS, and hope someone out there can help.

First, does anyone have a good formula for calculating distance between two points? Currently, I'm using the following, but would appreciate a formula that has a little more solid cartographical foundation:

longlen=69*(cos(lat*arcos(-1)/180)); y1len=69*(cos(lat1*arcos(-1)/180)); distx=69*(lat1-lat); disty=(long1-long)*((longlen+y1len)/2); distance=round(sqrt(sum(distx**2,disty**2)));

Secondly, is there formula/method/macro for determining if a point lies inside a given irregular polygon (i.e., a county or state)? I have a dataset with information on several thousand cities and towns, but it doesn't include county FIPS number. I'd like to be able to merge it with the mapping data from SAS and keep only the localities that are within the boundaries of a particular county. At the moment, I'm using a rather kludgy method that I would much rather replace. Any pointers to good cartographic texts would also be appreciated.

Thanks, Keith


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