sas >> Converting Latitude/Longitude (decimal degrees) to Bearing?

by anderson115 » Wed, 13 Jun 2007 04:53:03 GMT

Does someone have a formula to convert the lat and lon from two
locations (A and B) to bearings (location B relative to location A)?



sas >> Converting Latitude/Longitude (decimal degrees) to Bearing?

by Mterjeson » Wed, 13 Jun 2007 05:01:05 GMT


Hi,

Here are some posts to get you started:

http://listserv.uga.edu/cgi-bin/wa?A2=ind0605D&L=sas-l&P=R6483

http://listserv.uga.edu/cgi-bin/wa?A2=ind0511C&L=sas-l&P=R32434




Mark Terjeson
Senior Programmer Analyst, IM&R
Russell Investments
253-439-2367


Russell
Global Leaders in Multi-Manager Investing





-----Original Message-----
From: SAS(r) Discussion [mailto: XXXX@XXXXX.COM ] On Behalf Of
XXXX@XXXXX.COM
Sent: Tuesday, June 12, 2007 1:53 PM
To: XXXX@XXXXX.COM
Subject: Converting Latitude/Longitude (decimal degrees) to Bearing?

Does someone have a formula to convert the lat and lon from two
locations (A and B) to bearings (location B relative to location A)?



sas >> Converting Latitude/Longitude (decimal degrees) to Bearing?

by BD9439 » Thu, 14 Jun 2007 05:28:40 GMT

Hi

Here's a little SAS example to calculate both the bearing and the
distance between two points. It's a bit long-winded for illustration
purposes. I got a lot of help from this web site:

http://www.movable-type.co.uk/scripts/latlong.html

There are two different distance calculation techniques used and either
works for me. I don't claim to understand how any of this works; I just
have this in my SAS toolbox. There are many online discussions out
there if you're interested. It seems to depend on the degree of
accuracy you need. And if you need distance in kilometers, change the
earth radius constant to kilometers (see the comment).

Hope this helps; the code follows.

Bob

data SAMPLE_TABLE1(keep=deg_lat1 deg_lon1 deg_lat2 deg_lon2 distance1
distance2
deg_bearing bearing_txt);
if _n_ = 1 then do;
/* Define Pi and the Radius of the Earth as constants */
Pi = constant('pi'); /* Use the SAS function to improve precision
*/
* REarth = 6367; /* Kilometers */
REarth = 3956.2704; /* Miles */
end;
retain Pi REarth;

/* First point */
deg_lon1 = -81.2238;
deg_lat1 = 35.25927;

/* Second point */
deg_lon2 = -81.1492;
deg_lat2 = 35.22143;

/* First convert degrees to radians */
rad_lon1 = deg_lon1 * pi / 180;
rad_lat1 = deg_lat1 * pi / 180;
rad_lon2 = deg_lon2 * pi / 180;
rad_lat2 = deg_lat2 * pi / 180;

/* Law of Cosines for Spherical Trigonometry (uses radius) */
distance1 = REarth * arcos( ( cos(rad_lat1) * cos(rad_lat2) *
cos(rad_lon1-rad_lon2) )
+ ( sin(rad_lat1) * sin(rad_lat2) ) );
/* Haversine Formula (uses diameter) */
A = sin( (rad_lat2 - rad_lat1)/2.0 )**2
+ ( cos(rad_lat1) * cos(rad_lat2) * sin((rad_lon2 -
rad_lon1)/2.0)**2 );
distance2 = (REarth * 2) * atan2(sqrt(A),sqrt(1-A));

/* Calculate bearing */
rad_Bearing = mod(atan2(sin(rad_lon1-rad_lon2)*cos(rad_lat2),

cos(rad_lat1)*sin(rad_lat2)-sin(rad_lat1)*cos(rad_lat2)*cos(rad_lon1-rad
_lon2)), 2*Pi);

/* Convert bearing to degrees and create display variable as
degrees-minutes-seconds */
deg_Bearing = rad_Bearing * 180 / Pi;

Degrees = Int(abs(deg_Bearing));
Minutes = (abs(deg_Bearing) - Degrees) * 60;
Seconds = round((Minutes - Int(Minutes)) * 60);
Bearing_txt = put(degrees,3.) || 'B0'x || put(minutes,2.) || "'" ||
put(seconds,2.) || '"';
run;


-----Original Message-----
From: SAS(r) Discussion [mailto: XXXX@XXXXX.COM ] On Behalf Of
XXXX@XXXXX.COM
Sent: Tuesday, June 12, 2007 1:53 PM
To: XXXX@XXXXX.COM
Subject: Converting Latitude/Longitude (decimal degrees) to Bearing?

Does someone have a formula to convert the lat and lon from two
locations (A and B) to bearings (location B relative to location A)?


Converting Latitude/Longitude (decimal degrees) to Bearing?

by davidlcassell » Thu, 14 Jun 2007 09:51:03 GMT

XXXX@XXXXX.COM replied:


Good code is always appreciated. I don't think it is too long for SAS-L.




It's basic spherical trigonometry. Behavior of polygons on spherical
surfaces. Of course, it's approximate, since the earth is not really
spherical, but it's a pretty darn good approximation in most cases.



HTH,
David
_________________________________________________________________
Get a preview of Live Earth, the hottest event this summer - only on MSN
http://liveearth.msn.com ?source=msntaglineliveearthhm


Converting Latitude/Longitude (decimal degrees) to Bearing?

by anderson115 » Fri, 15 Jun 2007 07:15:43 GMT

n Jun 13, 8:51 pm, XXXX@XXXXX.COM (David L Cassell) wrote:

Mark, Bob, and David-
Thank you all for you input and advice. i was able to utilize all your
input to make my calculation. I appreciate you all taking the time to
respond.

Aaron



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*********************************************************************************

1391       EXECUTE(
1392           declare global temporary table qsrv
1393                    (   Id               char    (29)
1394                      , First_Srv_Dt     date
1395                      , rslt_cd          char     (13)
1396                      , res_val          char     (18)
1397                      , Num_Res_Val      smallint
1398                    )
1399           in "&sestblspc"
1400           on commit preserve rows not logged
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1403       EXECUTE(
1404           insert into session.qsrv
1405           select qu.Id
1406                , qu.dos
1407                , qu.rslt_cd
1408                , qu.res_val,
1409
1410          CASE
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1412
1417               qu.lr_res_val= ' '
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1421             from &clmschema..v_l_data     qu
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1423               on qu.Id               = np.Id
1424
1425       ) by mYconnect;
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       character string argument of the function "INTEGER".  SQLSTATE=22018
********************************************************************************************

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data base_ (drop =_:);
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run;

********************************************************************
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Thank You in advance,



Irin







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