Node:ArcTan, Next:Arg, Previous:Append, Up:Reference

### ArcTan

#### Synopsis

    function ArcTan (x: Real): Real;

or

    function ArcTan (z: Complex): Complex;

#### Description

`ArcTan` returns the (principal value of the) arcus tangent of the argument. The result is in the range `-Pi / 2 < ArcTan (x) < Pi / 2` for real arguments.

#### Conforming to

The function `ArcTan` is defined in ISO 7185 Pascal; its application to complex values is defined in ISO 10206 Extended Pascal.

#### Example

    program ArcTanDemo;
    begin
      { yields 3.14159 as ArcTan (1) = Pi / 4 }
      WriteLn (4 * ArcTan (1) : 0 : 5)
    end.

#### See also

Sin, Cos, Ln, Arg.