Node: ArcTan, Next: Arg, Previous: ArcSin, 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

`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

ArcSin, ArcCos, Sin, Cos, Ln, Arg.