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Une des fonctions les plus communes de la géographie et des systèmes modernes, c'est le calcul de la distance géographique entre deux coordonnées de Longitude et de Latitude.
Il n'y a aucune nécessité de grande connaissance en trigonométrie pour arriver à se genre de calcul dans le format qu'on le souhaite, Km, Miles ou Miles Nautiques.
Ainsi, si vous savez les coordonnéss suivantes:
| Montréal |
45 31N |
73 34O |
| Paris |
48 50N |
2 20E |
A l'aide du code source ASP .NET suivant, vous trouvez la réponse que vous souhaitez:
<%@ Page Language="VB" %>
<script runat="server">
Function CoordToDeltaKm( _
Q1Latitude As Double,Q1LatiDeg As Double,Q1LatiDirection As Char, _
Q1Longitude As Double,Q1LongDeg As Double,Q1LongDirection As Char, _
Q2Latitude As Double,Q2LatiDeg As Double,Q2LatiDirection As Char, _
Q2Longitude As Double,Q2LongDeg As Double,Q2LongDirection As Char)
Dim a1,b1,a2,b2,RawDelta As Double
a1=(Q1Latitude+(Q1LatiDeg/60))*Math.PI/180
If Q1LatiDirection="N"Then
a1=-a1
End If
b1=(Q1Longitude+(Q1LongDeg/60))*Math.PI/180
If Q1LongDirection="O"Then
b1=-b1
End If
a2=(Q2Latitude+(Q2LatiDeg/60))*Math.PI/180
If Q2LatiDirection="N"Then
a2=-a2
End If
b2=(Q2Longitude+(Q2LongDeg/60))*Math.PI/180
If Q2LongDirection="O"Then
b2=-b2
End If
RawDelta=Math.ACos(Math.Cos(a1)*Math.Cos(b1)*Math.Cos(a2)*Math.Cos(b2) + Math.Cos(a1)*Math.Sin(b1)*Math.Cos(a2)*Math.Sin(b2) + Math.Sin(a1)*Math.Sin(a2))
CoordToDeltaKm=RawDelta*6378.0
End Function
Function CoordToDeltaStatuteMiles( _
Q1Latitude As Double,Q1LatiDeg As Double,Q1LatiDirection As Char, _
Q1Longitude As Double,Q1LongDeg As Double,Q1LongDirection As Char, _
Q2Latitude As Double,Q2LatiDeg As Double,Q2LatiDirection As Char, _
Q2Longitude As Double,Q2LongDeg As Double,Q2LongDirection As Char)
Dim a1,b1,a2,b2,RawDelta As Double
a1=(Q1Latitude+(Q1LatiDeg/60))*Math.PI/180
If Q1LatiDirection="N"Then
a1=-a1
End If
b1=(Q1Longitude+(Q1LongDeg/60))*Math.PI/180
If Q1LongDirection="O"Then
b1=-b1
End If
a2=(Q2Latitude+(Q2LatiDeg/60))*Math.PI/180
If Q2LatiDirection="N"Then
a2=-a2
End If
b2=(Q2Longitude+(Q2LongDeg/60))*Math.PI/180
If Q2LongDirection="O"Then
b2=-b2
End If
RawDelta=Math.ACos(Math.Cos(a1)*Math.Cos(b1)*Math.Cos(a2)*Math.Cos(b2) + Math.Cos(a1)*Math.Sin(b1)*Math.Cos(a2)*Math.Sin(b2) + Math.Sin(a1)*Math.Sin(a2))
CoordToDeltaStatuteMiles=RawDelta*3963.1
End Function
Function CoordToDeltaNauticalMiles( _
Q1Latitude As Double,Q1LatiDeg As Double,Q1LatiDirection As Char, _
Q1Longitude As Double,Q1LongDeg As Double,Q1LongDirection As Char, _
Q2Latitude As Double,Q2LatiDeg As Double,Q2LatiDirection As Char, _
Q2Longitude As Double,Q2LongDeg As Double,Q2LongDirection As Char)
Dim a1,b1,a2,b2,RawDelta As Double
a1=(Q1Latitude+(Q1LatiDeg/60))*Math.PI/180
If Q1LatiDirection="N"Then
a1=-a1
End If
b1=(Q1Longitude+(Q1LongDeg/60))*Math.PI/180
If Q1LongDirection="O"Then
b1=-b1
End If
a2=(Q2Latitude+(Q2LatiDeg/60))*Math.PI/180
If Q2LatiDirection="N"Then
a2=-a2
End If
b2=(Q2Longitude+(Q2LongDeg/60))*Math.PI/180
If Q2LongDirection="O"Then
b2=-b2
End If
RawDelta=Math.ACos(Math.Cos(a1)*Math.Cos(b1)*Math.Cos(a2)*Math.Cos(b2) + Math.Cos(a1)*Math.Sin(b1)*Math.Cos(a2)*Math.Sin(b2) + Math.Sin(a1)*Math.Sin(a2))
CoordToDeltaNauticalMiles=RawDelta * 3443.9
End Function
</script>
<%
Response.Write("Distance entre Montréal et Paris en Km: " &CStr(CoordToDeltaKm(45, 31,"N",73, 34,"O",48, 50,"N", 2, 20,"E")) &"<BR>")
Response.Write("Distance entre Montréal et Paris en Miles: " &CStr(CoordToDeltaStatuteMiles(45, 31,"N", 73, 34,"O", 48, 50,"N", 2, 20,"E")) &"<BR>")
Response.Write("Distance entre Montréal et Paris en Miles Nautique: " &CStr(CoordToDeltaNauticalMiles(45, 31,"N", 73, 34,"O", 48, 50,"N", 2, 20,"E")) &"<BR>")
%>
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on obtiendra le résultat suivant:
Distance entre Montréal et Paris en Km: 5510.16761889
Distance entre Montréal et Paris en Miles: 3423.85470217
Distance entre Montréal et Paris en Miles Nautique: 2975.30044884
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