Public Function arcsin(x As Double) As Double
   arcsin(x) = Atn(x / Sqr(-x * x + 1))
End Function
Public Function arccos(x As Double) As Double
   arccos(x) = Atn(-x / Sqr(-x * x + 1)) + 2 * Atn(1)
End Function


以上是我编的一个函数，提示"函数调用必须返回变体或对象",请问我该如何改正呢？