Code:
<% ' This routine calculates the distance between two points ' (given the latitude/longitude of those points). It is being 'used to calculate distance between two ZIP Codes or Postal 'Codes using our ZIPCodeWorld(TM) and PostalCodeWorld(TM) ' products. 'Definitions ' South latitudes are negative, east longitudes are 'positive ' Passed to function 'lat1, lon1 = Latitude and Longitude of point 1 '(in decimal degrees) 'lat2, lon2 = Latitude and Longitude of point 2 '(in decimal degrees) 'unit = the unit you desire for results 'where 'M' is statute miles (default) ''K' is kilometers 'N' is nautical miles ''United States ZIP Code/ Canadian Postal Code databases with 'latitude & longitude are available at 'http//www.zipcodeworld.com 'For enquiries, please contact sales@zipcodeworld.com 'Official Web site http//www.zipcodeworld.com ' 'Hexa Software Development Center ¸ All Rights Reserved 2003 ' ' const pi = 3.14159265358979323846 Function distance(lat1, lon1, lat2, lon2, unit) Dim theta, dist theta = lon1 - lon2 dist = sin(deg2rad(lat1)) * sin(deg2rad(lat2)) + cos(deg2rad(lat1)) * cos(deg2rad(lat2)) * cos(deg2rad(theta)) dist = acos(dist) dist = rad2deg(dist) distance = dist * 60 * 1.1515 Select Case ucase(unit) Case "K" distance = distance * 1.609344 Case "N" distance = distance * 0.8684 End Select End Function ' ' This function get the arccos function from arctan function ' Function acos(rad) If Abs(rad) <> 1 Then acos = pi/2 - Atn(rad / Sqr(1 - rad * rad)) ElseIf rad = -1 Then acos = pi End If End function ' ' This function converts decimal degrees to radians ' Function deg2rad(Deg) deg2rad = cdbl(Deg * pi / 180) End Function ' ' This function converts radians to decimal degrees ' Function rad2deg(Rad) rad2deg = cdbl(Rad * 180 / pi) End Function 'Demo response.write distance(32.9697, -96.80322, 29.46786, -98.53506, "M") & " Miles<br>" response.write distance(32.9697, -96.80322, 29.46786, -98.53506, "K") & " Kilometers<br>" response.write distance(32.9697, -96.80322, 29.46786, -98.53506, "N") & " Nautical Miles<br>" %>