25 Aug
2009
25 Aug
'09
3:01 p.m.
Bulat Ziganshin schrieb:
Hello Henning,
Tuesday, August 25, 2009, 6:11:00 PM, you wrote:
digits = iterate (`div` 10) >>> takeWhile (>0) >>> length
This needs quadratic time with respect to the number of digits, doesn't it?
why?
Because division by 10 needs linear time.
i think that `show` uses pretty the same way to build list of digits, so we just omit unneeded computations
I hope that 'show' will not need quadratic time but will employ a more efficient algorithm that is certainly implemented in the GNU multiprecision library. I assume that a division by 10^(2^k) will require about 2^k * k operations. At least, it should be considerably faster than repeatedly dividing by 10.