Never work with arrays of that length. What's worse, it was wrong. Better is
(3 :'~.b, y%|. b=.a#~ 0=y|~ a=.>:i. <.%:y')36 1 2 3 4 6 9 12 18 36 R.E. Boss (Add your info to http://www.jsoftware.com/jwiki/Community/Demographics ) > -----Original Message----- > From: [email protected] [mailto:programming- > [email protected]] On Behalf Of Roger Hui > Sent: dinsdag 10 juni 2014 21:27 > To: Programming forum > Subject: Re: [Jprogramming] Shorten a verb > > Yes, it's shorter, but it performs not so well on large arguments. Try it > on !20x, for example. Henry's solution does not have this problem. > > > > > On Tue, Jun 10, 2014 at 12:11 PM, R.E. Boss <[email protected]> wrote: > > > Remarkably, I was just thinking about such a divisor verb (since I needed > > it > > to represent an array as a matrix) and came to > > > > (3 :('b, y%|. b=.a#~ 0=y|~ a=.i.&.<: >.%:y'))51 > > 1 3 17 51 > > > > (3 :('b, y%|. b=.a#~ 0=y|~ a=.i.&.<: >.%:y'))360 > > 1 2 3 4 5 6 8 9 10 12 15 18 20 24 30 36 40 45 60 72 90 120 180 360 > > > > Or tacitly > > (](([, (% |.))]#~ 0=|~) [:i.&.<: >.@%:) > > > > > > R.E. Boss > > > > (Add your info to > http://www.jsoftware.com/jwiki/Community/Demographics ) > > > > > > > > > -----Original Message----- > > > From: [email protected] > [mailto:programming- > > > [email protected]] On Behalf Of Roger Hui > > > Sent: dinsdag 10 juni 2014 19:19 > > > To: Programming forum > > > Subject: Re: [Jprogramming] Shorten a verb > > > > > > From http://www.jsoftware.com/jwiki/Essays/Divisors > > > > > > div=: /:~ @: , @: > @: (*/&.>/) @: ((^ i.@>:)&.>/) @: (__&q:) > > > div 360 > > > 1 2 3 4 5 6 8 9 10 12 15 18 20 24 30 36 40 45 60 72 90 120 180 360 > > > > > > > > > > > > > > > > > > On Tue, Jun 10, 2014 at 10:10 AM, Jon Hough <[email protected]> > > > wrote: > > > > > > > My attempt at making a verb that finds the total of all proper divisors > > of > > > > an integer seems to work. > > > > e.g. if n = 12, the sum of proper divisors is 1 +2 +3+4+6 = 16 (note 12 > > is > > > > not included) > > > > This verb is actually equal to the "sigma function" minus n.Wikipedia > > > > explanation: http://en.wikipedia.org/wiki/Divisor_function > > > > (I essentially used the equation for sigma_x(n) where x = 1) > > > > my verb: > > > > > > > > sum =.(((*/@:-&1@:{.)%~(*/@:-&1@:({.^(1&+@:,@:}.))))@:(2&p:))-] > > > > This seems ok, but is not aesthetically pleasing, and seems to be very > > > > bracketty, and given that the mathematical equation is pretty concise I > > am > > > > surprised the J verb is so long. If anyone knows a nicer way of doing > > this > > > > I would be grateful to see it. > > > > Regards. > > > > ---------------------------------------------------------------------- > > > > 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 ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
