爱华网在业务上经常需要计算2个地点的距离，如台风路径预报误差。两点之间的距离实际上是球面距离，参考了网上搜索后，编写了VB源程序，供大家参考。yry,2012.5Haikou
Const EARTH_RADIUS = 6378.137
Const pi = 3.1415926535898
Public IS_stationP As Boolean
Private Sub Command1_Click()
Dim lon1 As Double, lon2 As Double, lat1 As Double, lat2 AsDouble
lon1 = Val(Text1)
lat1 = Val(Text2)
lon2 = Val(Text3)
lat2 = Val(Text4)
Lab_距离.Caption = "近似距离: " &Format(GetDistance(lat1, lon1, lat2, lon2), "####.0")& " 公里"
End Sub
Function rad(ByVal d As Double) As Double
rad = d * pi / 180
End Function
'知道两点经纬度，求近似距离
Public Function GetDistance(lat1 As Double, lng1 As Double, lat2 AsDouble, lng2 As Double) As Double
Dim radlat1 As Double, radlat2 As Double
Dim a As Double, b As Double, s As Double, Temp As Double
radlat1 = rad(lat1)
radlat2 = rad(lat2)
a = radlat1 - radlat2
b = rad(lng1) - rad(lng2)
Temp = Sqr(Sin(a / 2) ^ 2 + Cos(radlat1) * Cos(radlat2) * Sin(b /2) ^ 2)
s = 2 * Atn(Temp / Sqr(-Temp * Temp + 1))'没有反正弦函数，网上找了个
s = s * EARTH_RADIUS
GetDistance = s
End Function
