The 2 fastest versions I've found on my computer: 100 timespacex '( + <: ) */ +:@:*:^:2 ] 1024 16' 3.4112e_6 4352
100 timespacex '(+ <:) +:^:14 *:^:4 ] 8 ' 5.5744e_6 3072 The &. x: is obviously much more generic and practical for generating "medium" sized numbers. 100 timespacex ' 2 <: &. x:@^ 63 ' 8.064e_6 5632 The importance of all this, btw, is that there is a significant size penalty to storing extended integers, as well as a time/space compromise in working with them. ----- Original Message ----- From: 'Pascal Jasmin' via Programming <[email protected]> To: "[email protected]" <[email protected]> Cc: Sent: Monday, May 26, 2014 2:35:14 PM Subject: Re: [Jprogramming] 2^63 Might this be the fastest way of getting 2^63-1, without x: ? (<: + ] ) +:^:14 *:^:4 ] 8 9223372036854775807 worth noting: +:^:62 ] 2 9.22337e18 +:^:61 ] 2 4611686018427387904 2 <: &. x:@^ 63 9223372036854775807 --- actually this is probably best: 2 <: &. x:@^ 63 9223372036854775807 3!:0 ] 2 <: &. x:@^ 63 4 ----- Original Message ----- From: Raul Miller <[email protected]> To: Programming forum <[email protected]> Cc: Sent: Monday, May 26, 2014 2:02:01 PM Subject: Re: [Jprogramming] 2^63 Here's an interesting bug (I can't call this kind of issue a feature if it's not documented in the dictionary, can I?): 9223372036854775809 9223372036854775807 (And that's probably more important than the "using ^" issue.) Thanks, -- Raul On Mon, May 26, 2014 at 1:55 PM, 'Pascal Jasmin' via Programming < [email protected]> wrote: > is there a way to get ^ to make a 64bit number without it being extended > precision? I guess an efficient alternative to ^ if that is not possible: > > 2^63 > 9.22337e18 > 2^63x > 9223372036854775808 > 9223372036854775808 > 9223372036854775807 > > Note that the last line is probably a problem. The answer is the largest > non extended integer, but still unwelcome change from the input. > > 9223372036854775808-1 > 9223372036854775806 > 9223372036854775809-1 > 9223372036854775806 > > I guess this works > > (<: + ] ) 4611686018427387904 > NB. 2^62x > 9223372036854775807 > > ---------------------------------------------------------------------- > 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
