Hi,
Can someone explain to me the behavior of this function when applied
to different kind of numbers.
(defn prime-factors [n]
(loop [f 2 n n res []]
(cond
(<= n 1) res
(zero? (rem n f)) (recur f (quot n f) (conj res f))
:else (recur (inc f) n res))))
Problem 1 (solved): If you use (= n 1) in the first cond clause, the
function may not terminate because (= 1 1.0) may be false. But we all
know that :)
Problem 2: Now compare theses function calls
(prime-factors (Math/pow 2 58))
(prime-factors (bigdec (Math/pow 2 58)))
(prime-factors (bigint (bigdec (Math/pow 2 58))))
The last two function calls are really really slow.
- Is this only a problem of rem/quot slow on big numbers ?
-
Laurent
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