PHILBERT LUHUNGA philuhunga at yahoo.com
Mon Feb 16 04:34:29 EST 2015

```Dear David, thank you. Let me try to learn the script, but it seems to be complexthank you again, if you can simplify it will appreciate.  AS EVER
LUHUNGA

--------------------
Philbert Modest Luhunga
University of Pretoria
Department of Geography,Geoinformatics and Meteorology
Private Bag X20 Hatfield 0028 South Africa
Tel +27 (0) 12 420 5164
Fax +27 (0) 12 420 6385
Mobile:+ 27826228060
From: Davide Sacchetti <davide.sacchetti at arpal.gov.it>
Sent: Monday, February 16, 2015 10:42 AM

function dist(lon1,lat1,lon2,lat2)
* Distance between two points on the Earth surface
_At=6371229
_PI=3.141592654
_D2R=_PI/180
_R2D=180/_PI
Theta1=lon1*_D2R;Phi1=(90-lat1)*_D2R
'd sin('Phi1')*cos('Theta1')'
x1=subwrd(result,4)
'd sin('Phi1')*sin('Theta1')'
y1=subwrd(result,4)
'd cos('Phi1')'
z1=subwrd(result,4)
Theta2=lon2*_D2R;Phi2=(90-lat2)*_D2R
'd sin('Phi2')*cos('Theta2')'
x2=subwrd(result,4)
'd sin('Phi2')*sin('Theta2')'
y2=subwrd(result,4)
'd cos('Phi2')'
z2=subwrd(result,4)
*    x=y1*z2-y2*z1
*    y=x2*z1-x1*z2
*    z=x1*y2-x2*y1
*    d2=x*x+y*y+z*z
Alpha='acos( cos('Phi1')*cos('Phi2') +
cos('Theta1'-'Theta2')*sin('Phi1')*sin('Phi2'))'
*    'd asin(sqrt('d2'))'
*    'd acos('Alpha')'
'd 'Alpha
*say 'T,P: 'Theta1' 'Phi1
*say 'T,P: 'Theta2' 'Phi2
*say 'A,cA: 'Alpha' 'subwrd(result,4)
return (subwrd(result,4)*_At)

On Mon, 2015-02-16 at 07:45 +0000, PHILBERT LUHUNGA wrote:
> Hi does any one knows how to compute distance between two latitude and
> longitude points in GrADs. I have two points
> lon1=30
> lat1=-6
> lon2=30.6
> lat2=-6.4
>
>
>
> AS EVER
> LUHUNGA
>
> --------------------
> Philbert Modest Luhunga
> University of Pretoria
> Department of Geography,Geoinformatics and Meteorology
> Private Bag X20 Hatfield 0028 South Africa
> Tel +27 (0) 12 420 5164
> Fax +27 (0) 12 420 6385
> Mobile:+ 27826228060
> Email address: philuhunga at yahoo.com
> _______________________________________________

--
Davide Sacchetti
Centro Funzionale Meteo Idrologico di Protezione Civile della Regione Liguria
ARPAL Unità Tecnica Complessa di livello Regionale
V.le Brigare Partigiane 2 16121 Genova (I)
tel: +39 010 6437535                    fax: +39 010 6437520

mail: davide.sacchetti at arpal.gov.it    web: www.meteoliguria.it

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