
tan(+Number, -Result)

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



Arguments
   Number              A number.
   Result              A variable, 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).
     5 --- Result is a number but not a float or breal.
    24 --- Number is not of a numeric type.
    24 --- Result is neither a number nor a variable.
    20 --- Illegal arithmetic operation:  Number is (2k +1) * pi/2 for    every integer k.

Examples
   
Success:
      tan(0, 0.0).
      tan(12.3, Result).      (gives Result = -0.272854)
      tan(-1, Result).        (gives Result = -1.55741)
Fail:
      tan(1, 0.0).
Error:
      tan(A, 6.0).                      (Error 4).
      tan(0, 0).                        (Error 5).
      X is pi/2, tan(X, Result).        (Error 20).
      tan(10.3 + 2, -0.272854).         (Error 24).
      tan(5, r).                        (Error 24).





See Also
   is / 2
