Preliminary benchmarks: ts=: 6!:2 , 7!:[EMAIL PROTECTED] x=: 1e6 [EMAIL PROTECTED] 2e6 ts 'Expression'
Expression J6.02x J6.01 Factor x <[EMAIL PROTECTED] 512 0.0054822 4.19507e6 0.136416 2.09723e7 23.80 5.00 x <[EMAIL PROTECTED] 17 0.0213073 4.19507e6 0.154837 2.09723e7 7.27 5.00 ----- Original Message ----- From: Roger Hui <[EMAIL PROTECTED]> Date: Friday, October 20, 2006 8:24 am Subject: Re: [Jprogramming] Interger division, the faster one > That is a good idea. The improvement should be > around a factor of 10 in time and a factor of 2 > in space. > > > > ----- Original Message ----- > From: Oleg Kobchenko <[EMAIL PROTECTED]> > Date: Friday, October 20, 2006 1:03 am > Subject: [Jprogramming] Interger division, the faster one > > > I expected there'd be special code for (<[EMAIL PROTECTED]). Alas, > > > > 6!:2 '(i.1e6) % 256' > > 0.0246238 > > 6!:2 '(i.1e6) <[EMAIL PROTECTED] 256' > > 0.208256 > > 6!:2 '(i.1e6) <.@:% 256' > > 0.236405 > > > > For powers of 2 there's still > > > > 6!:2 '_8 (33 b.) (i.1e6)' > > 0.0162501 > > ((i.1e6) <[EMAIL PROTECTED] 256) -: _8 (33 b.) (i.1e6) > > 1 > > > > > > Viewmat improvement > > ~~~~~~~~~~~~~~~~~~~ > > > > Thus this change makes complex viewmat ~x3.5 faster. > > > > k=. <.256*x - <. x NB. both times > > ... > > mat=. _8(33 b.) (t *"2 k) + b (*"2) 256-k > > ... > > mat=. _8(33 b.) (t * k) + b * 256-k > > ... > > mat=. 256 #. mat ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
