Mathematical term for VB functions Atn or Atan

Hi there,

Atn (in VB6) or Atan (in newer version) returns a Double value containing the angle whose tangent is the specified number.

Forget about programming and VB - how would I express this in mathematical terms? If I were to talk to a mathematician (which I obviously don't do very often, otherwise I would not ask this question), what would I call an angle whose tangent is the specified number?

Thanks for your enlightenment!

Arctangent

I was taught both 'arctangent' and 'inverse tan' are acceptable. Although inverse tan might be more for just pronouncing how it's written: tan^-1. Arctangent is probably more correct.