(rationalize num)
returns the rational value of num
<pre>\r
user=> (rationalize 1.5)\r
3/2\r
</pre>
user=> (rationalize Math/PI)
3141592653589793/1000000000000000
user=> (rationalize (Math/sqrt 2))
14142135623730951/10000000000000000
(rationalize 2/4)
;; => 1/2
(rationalize 4/2)
;; => 2
(rationalize 2)
;; => 2
(rationalize 2.0)
;; => 2N
;; To quickly convert a mixed number to an improper fraction,
;; multiply the denominator
;; by the whole number and add to the numerator
(= (+ 20 3/4) (rationalize (/ (+ (* 20 4) 3) 4)))
;; => true