-:<:sqrt 5 0.618034 Linda -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Roger Hui Sent: Thursday, December 12, 2013 5:40 PM To: Programming forum Subject: Re: [Jprogramming] Under for fun & profit
sqrt1=: (] -:@+ %)^:_~ x -: *: sqrt1 x=: 100 ?@$ 1000 1 x -: *: sqrt1 x=: 100 ?@$ 0 1 On Thu, Dec 12, 2013 at 1:31 PM, Roger Hui <[email protected]>wrote: > Ooops. A longer but correct solution. Can probably be shortened. > > sqrt=: (0.5 * ] + %)^:_ ~ > sqrt 3 > 1.73205 > sqrt 17 > 4.12311 > > > > > On Thu, Dec 12, 2013 at 1:29 PM, Roger Hui <[email protected]>wrote: > >> sqrt=: -:@(+%)^:_~ >> sqrt 3 >> 1.78078 >> sqrt 17 >> 8.55842 >> >> >> >> On Thu, Dec 12, 2013 at 1:22 PM, William Tanksley, Jr < >> [email protected]> wrote: >> >>> I'm clueless -- how would you implement one of the more formally >>> correct solutions (Newton's, Babylonian, exhaustive search, or >>> random probing)? K did pretty well. >>> >>> -Wm >>> >>> >>> On Thu, Dec 12, 2013 at 11:09 AM, Dan Bron <[email protected]> wrote: >>> > There is a stack exchange dedicated to code golfing, >>> > http://codegolf.stackexchange.com/ . During free moments at work, >>> > I >>> find >>> > posting J solutions is a good way to relieve stress. >>> > >>> > Today I came across a competition to reimplement square root in as >>> > few characters as possible [1]. Most languages copped out and >>> > simply >>> restated >>> > sqrt as ^&0.5 to minimize their golf score. (I did this too, to >>> > allow apples-to-apples comparisons). >>> > >>> > But the C++ entry caught my eye: exp(log(x)/2)) . This is an >>> interesting >>> > approach, and gives us an opportunity to highlight some of the >>> advantages >>> > of J's notaton. Leaving aside the question of syntax, even >>> > expressing >>> the >>> > 4 primitives in that expression (exp, log, x, 2) would cost most >>> languages >>> > 8 characters. But not in J. In J, we do NOT need: >>> > >>> > - To name variables (so no "x") >>> > - To name the constant 2 (in this particular case) >>> > - To delimit functions from arguments using parentheses >>> > - To explicitly instruct the intreprter to undo the log by >>> > typing >>> "exp". >>> > >>> > This last freebie is perhaps the most satisfying. We just tell >>> > the interpreter that we want to operate "log space", and let J >>> > figure out >>> the >>> > exp for itself. >>> > >>> > -:&.^. >>> > >>> > Six characters. Less than it takes to write "log" and "exp" >>> > separated >>> by a >>> > single space! >>> > >>> > -Dan >>> > >>> > [1] >>> > >>> http://codegolf.stackexchange.com/questions/73/reimplementing-square >>> -root/15856 >>> > >>> > ------------------------------------------------------------------ >>> > ---- 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 ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
