**Public Function ATAN( _
ByVal vX As Variant _
) As Variant**

**"Inverse Tangent" or "Arctangent" **

Angle whose tangent is X.

Inverse of the Tangent function.

**Examples:** ATan(-0.5) = -0.463647609000806
ATan(0) = 0
ATan(0.5) = 0.463647609000806
ATan(1) = 0.785398163397448
ATan(1.5) = 0.982793723247329
ATan(2) = 1.10714871779409
ATan(2.5) = 1.19028994968253
ATan(3) = 1.24904577239825
ATan(3.5) = 1.29249666778979
ATan("2.3|-4.5") = "1.4781469556746|-0.176543708945617"

**See also:** Tangent Function
ASin Function
ACos Function
ATanH Function
Atn Function (Visual Basic)

**vX:** Function returns the principal value of the angle whose tangent (expressed in radians) is vX. Function returns Null if vX is Null or cannot be fixed up to a real or complex number (as defined by the ComplexStringToReals function). Complex numbers are represented within strings as "R|I" where R is the real part and I is the imaginary part. Copyright 1996-1999 Entisoft

Entisoft Tools is a trademark of Entisoft.