【测绘算法】计算方位角

Public Const pi As Double = 3.14159265358979
Public Function Azimuth(x1 As Double, y1 As Double, x2 As Double, y2 As Double) As Double
  Dim dx As Double, dy As Double, temp As Double
  dx = x2 - x1: dy = y2 - y1
  If dy <> 0 Then
     temp = pi * (1 - Sgn(dy) / 2) - Atn(dx / dy)
     Azimuth = temp * 180 / pi
  Else
     Azimuth = IIf(dx > 0, 0, 180)
  End If
End Function