已知两点的经纬如何计算出两点的距离？

求助算法：

已知两点的经纬如何计算出两点的距离？

转载：已知两点的经纬度 一段实例代码： －－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－ Option Explicit

'Class Name:   ClsDistance 'Initiator:    Kewudemao 'Date:         April 28, 2003 'Description:  To calculate the distance between two point based on lat and lon. 'Modify:

'-----WGS 84 based parameters of earch------ Private Const R_A = 6378137     ' long Private Const R_B = 6356752     'short '------------------------------------------ Private Const PI = 3.1415926    'Pi

Private m_R As Double

Public Enum Distance_Mode  '      Miles = 0      Feet = 1 End Enum

Private Type PointType      lat As Double      lon As Double End Type

Private m_PointA As PointType Private m_PointB As PointType Private m_DistMode As Distance_Mode 'to get the parameters of DistanceMode Public Property Get Dist_Mode() As Distance_Mode     Dist_Mode = m_DistMode End Property

Public Property Let Dist_Mode(ByVal vNewValue As Distance_Mode)    m_DistMode = vNewValue End Property

Private Sub Class_Initialize()      m_R = (R_A + R_B) / 2 End Sub 'get the first point Public Function SetPointA(lat As Double, lon As Double) As Boolean      If (lat <= 90 And lat >= -90) And (lon >= -180 And lon <= 180) Then          m_PointA.lat = lat          m_PointA.lon = lon          SetPointA = True      Else          SetPointA = False      End If End Function 'get the second point Public Function SetPointB(lat As Double, lon As Double) As Boolean      If (lat <= 90 And lat >= -90) And (lon >= -180 And lon <= 180) Then          m_PointB.lat = lat          m_PointB.lon = lon          SetPointB = True      Else          SetPointB = False      End If End Function 'calculate the distance Public Function GetDistance() As Double     Dim angAB As Double     Dim tempV As Double     Dim tempD As Double          Dim angLatA As Double     Dim angLatB As Double     Dim angLonA As Double     Dim angLonB As Double               angLatA = m_PointA.lat / 180 * PI     angLonA = m_PointA.lon / 180 * PI     angLatB = m_PointB.lat / 180 * PI     angLonB = m_PointB.lon / 180 * PI          tempV = VBA.Cos(angLatA) * VBA.Cos(angLatB) * VBA.Cos(angLonB - angLonA) + VBA.Sin(angLatA) * VBA.Sin(angLatB)          Select Case tempV            Case 1    'angAB = 0                tempD = 0                       Case -1   'angAB = 180                tempD = m_R * PI            Case Else 'others                      angAB = VBA.Atn(-tempV / VBA.Sqr(-tempV * tempV + 1)) + 2 * VBA.Atn(1)                 tempD = m_R * angAB      End Select                       Select Case m_DistMode          Case Miles              tempD = tempD / 1609          Case Feet              tempD = tempD / 1609 * 5280                End Select          GetDistance = tempD      End Function －－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－