I meant that when v returns 0, f is not executed (and so will not print anything), but v is still queried until the iteration count is reached, like this:
f=: verb define smoutput 'res = ' , ":r=:2*y r ) v=: verb define smoutput 'v = ' , ": r=: (10 > ]) y r ) f^:v^:10 ] 1 v = 1 res = 2 v = 1 res = 4 v = 1 res = 8 v = 1 res = 16 v = 0 v = 0 v = 0 v = 0 v = 0 v = 0 16 Regards, Anton Wallgren On 26 May 2020, 12:04 +0200, 'Rob Hodgkinson' via Programming <[email protected]>, wrote: > I don’t agree, it does not proceed further. > > ([x] u^:v^:_ y) will actually stop when v returns 0 (does not skip or > continue executing) > > Here is a simple way to confirm this using a function f to do 2&* but which > also uses ’smoutput’ to output to the session log (print intermediate > results). > > f=: verb define > smoutput r=:2*y > r > ) > > f 5 > 10 NB. Intermediate print using smoutput > 10. NB. Result of f > > Test it… > a=:f 5 > 5. NB. It still prints within f via smoutput > > So now … > f^:(10>])^:3 ] 1 > 2 } > 4 } Intermediates from smoutpout (f called 3 times) > 8 } > 8 NB. Result returned (ran to completion) > f^:(10>])^:4 ] 1 > 2 } > 4 } Intermediates from smoutpoutn (f called 4 times) > 8 } > 16 } > 16 NB. Result returned (ran to completion) > f^:(10>])^:8 ] 1 > 2 } > 4 } Intermediates from smoutput (f called 4 times) > 8 } > 16 } > 16 NB. Result returned (aborted, so it stopped short and did not proceed > further) > > HTH, Rob > > > > On 26 May 2020, at 6:40 pm, Anton Wallgren <[email protected]> wrote: > > > > On closer inspection, f^:v^:n doesn’t seem to work (as I want it to). What > > it does is to skip evaluation each time v y returns 0. While this would > > work in my situation, as the stopping condition would remain true, it would > > of course be unnecessary (and inefficient) to keep checking this for the > > remainder of the iterations. > > > > Thanks, Anton Wallgren > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
