Question

I’d like to calculate atan2 in VBA, but I’m not sure if that function exists (or even where to find a canonical list of built-in VBA functions). I’m not using Excel so a worksheet call isn’t possible.

I could implement atan2 myself, but I’d prefer to avoid doing that if possible.

Answer 1

Maybe this code would suit you:

Private Const Pi As Double = 3.14159265358979

Public Function Atn2(y As Double, x As Double) As Double
  If x > 0 Then
    Atn2 = Atn(y / x)
  ElseIf x < 0 Then
    Atn2 = Sgn(y) * (Pi - Atn(Abs(y / x)))
  ElseIf y = 0 Then
    Atn2 = 0
  Else
    Atn2 = Sgn(y) * Pi / 2
  End If
End Function