
acos(+Number, -Result)

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



Arguments
   Number              A number.
   Result              A variable or float.

Type
   Arithmetic

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

    Result is acos(Number)

   which should be preferred for portability.

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


Modes and Determinism
   acos(+, -) is det

Exceptions
     4 --- Number is not instantiated (non-coroutining mode only).
     5 --- Result is a number but not a float
    24 --- Number is not of a numeric type.
    24 --- Result is neither a number nor a variable.
    20 --- Illegal arithmetic operation: Number is greater than 1 or less than -1.
   141 --- Argument is of type breal

Examples
   
Success:
      acos(1.0, 0.0).
      acos(-0.5, Result).       (gives Result = 2.0944)
      acos(0, Result).          (gives Result = 1.5708)
Fail:
      acos(1, 1.0).
Error:
      acos(A, 6.0).             (Error 4).
      acos(1, r).               (Error 5).
      acos(1, 0).               (Error 5).
      acos(2, Result).          (Error 20).
      acos(4 - 3, 0.0).         (Error 24).





See Also
   is / 2
