
rationalize(+Number, -Result)

   Converts Number into a compact rational number and unifies it with Result.



Arguments
   Number              A number.
   Result              A variable or rational number.

Type
   Arithmetic

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

    Result is rationalize(Number)

    which should be preferred.

   When Number is an integer, Result is a rational with denominator 1.

   When Number is already a rational, Result is identical to Number.

   When Number is a float, Result is a rational whose value approximates
   the value of the float to the accuracy of the float representation.
   rationalize/2 usually produces more compact rationals that rational/2.
   Both rationalize/2 and rational/2 produce results that convert back into
   the original float. rational/2 is usually faster than rationalize/2.

   Bounded reals cannot be converted to rationals.

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


Modes and Determinism
   rationalize(+, -) is det

Exceptions
     4 --- Number is not instantiated (non-coroutining mode only).
     5 --- Result is a number but not of type rational.
    24 --- Number is not of a numeric type.
    24 --- Result is neither a number nor a variable.
   141 --- Number is a bounded real

Examples
   
Success:
      rationalize(25, 25_1).
      rationalize(1.5, 3_2).
      rationalize(3_4,3_4).
      rationalize(9_12,3_4).
      rationalize(-6, Result).      (gives Result = -6_1)
      rationalize(0.1, Result).     (gives Result = 1_10)
Fail:
      rationalize(1, 2_1).
Error:
      rationalize(A, 1_3).                   (Error 4).
      rationalize(3, 3).                     (Error 5).
      rationalize(1, r).                     (Error 24).
      rationalize(4 + 2, 6_1).               (Error 24).
      rationalize(0.9__1.1, X).              (Error 141).





See Also
   rational / 2, is / 2
