
tan(+Number, -Result)

   Evaluates the trigonometric function tan(Number) and unifies the resulting
value with Result.



Arguments
   Number              A number.
   Result              Output: float or breal.

Type
   Arithmetic

Description
   This predicate is used by the ECLiPSe compiler to expand evaluable
   arithmetic expressions.  So the call to tan(Number, Result) is
   equivalent to

    Result is tan(Number)

    which should be preferred for portability.

   In coroutining mode, if Number is uninstantiated, the call to tan/2 is
   delayed until this variable is instantiated.




Modes and Determinism
   tan(+, -) is det

Exceptions
     4 --- Number is not instantiated (non-coroutining mode only).
    24 --- Number is not of a numeric type.
    20 --- Illegal arithmetic operation:  Number is (2k +1) * pi/2 for    every integer k.

Examples
   
Success:
    Result is tan(0).		% gives Result = 0.0
    Result is tan(12.3).        % gives Result = -0.272854
    Result is tan(-1).          % gives Result = -1.55741

Error:
    X is pi/2, tan(X). 		% arithmetic exception


See Also
   is / 2
