
rational(+Number, -Result)
-Result is rational(+Number)

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



Arguments
   Number              A number.
   Result              Output: rational number.

Type
   Arithmetic

Description

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

   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 is exactly equal
   to the value of the floating-point number. Since floats are usually
   approximations of the intended value, the results may look unintuitive
   and have unnecessarily large numerators and denominators. Use rationalize/2
   to produce the most compact rational that still converts back into the
   original float. rational/2 is usually faster than rationalize/2.

   Bounded reals cannot be converted to rationals.

   This predicate can be used as a function in arithmetic expressions.
   In coroutining mode, if Number is uninstantiated, the call to
   rational/2 is delayed until this variable is instantiated.


Modes and Determinism
   rational(+, -) is det

Exceptions
     4 --- Number is not instantiated (non-coroutining mode only).
    24 --- Number is not of a numeric type.
   141 --- Number is a bounded real

Examples
   
Success:
    Result is rational(25).	% gives Result = 25_1
    Result is rational(1.5).	% gives Result = 3_2
    Result is rational(3_4).	% gives Result = 3_4
    Result is rational(9_12).	% gives Result = 3_4
    Result is rational(-6).	% gives Result = -6_1
    Result is rational(0.1).    % gives Result = 3602879701896397_36028797018963968

Error:
    Result is rational(0.9__1.1, X).     % unimplemented


See Also
   rationalize / 2, is / 2
