But of course, J is GPL'd now, so it's now legal to use GMP in J. Someone's still going to need to do the integration work, of course...
(And it may very well be that that will expose some difficult corner cases.) -- Raul On Wed, Sep 2, 2015 at 3:50 AM, aai <agroeneveld...@gmail.com> wrote: > The main reason for speed difference is that big integer calculation in > Haskell is based on the GNU Multiple Precision Arithmetic Library (/GMP/), > much faster than J's extended precision number calculation. > > Op 2-9-2015 om 02:32 schreef Jon Hough: > >> In this talk https://www.youtube.com/watch?v=apBWkBDVlow >> the presenter attempts to show Haskell hasn't sacrificed speed for >> expressiveness by comparing a Java Fibonacci calculator to his Haskell >> one.(skip to the 18:00 mark).Essentially, to calculate the 475000th >> Fibonacci number, it took his Java program ~8 seconds, while the very terse >> Haskell program took ~6 seconds. >> So I tried to do the same in J. My first attempt, used a tacit, memoized >> verb >> fib1 =:1:`(($:@:<:) + ($:@:-&2))@.(2&<)M. >> >> >> However, this gives a stack error for large numbers (~100000). So I >> decided to make an imperative verb, >> >> >> fib2 =: 3 : 0 x1 =. x:1 x2 =. x:1 c =. 0 while. c < y do. tmp =. x1 x1 =. >> x2 x2 =. tmp + x1 c=.c+1 end. x2 >> >> >> >> >> >> >> >> >> >> >> >> >> ) >> >> >> This gets there, I can calculate the 475000th Fibonacci number, but >> >> >> timespacex 'fib2 475000' >> >> >> >> >> 36.183 1.31558e6 >> >> >> It takes 36 seconds (of course, my hardware is different to that in the >> presentation, but still...). >> >> >> Is there a speedier way to do this in J? Preferably a tacit one liner >> would also be good. >> >> >> Thanks, >> Jon >> >> ---------------------------------------------------------------------- >> For information about J forums see http://www.jsoftware.com/forums.htm > > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
