You are welcome, Ian. My reconstruction must be a bit more brute-force than Gene's version.
I ran this on 64 bit J on a system with 5G of memory: 7!:2 'BLT 8' 7247762688 This is with 8 byte integers, but still exceeds the 1073741824 bytes Gene's formula would estimate. -- David Mitchell Ian Clark wrote: > Thank you, David, for your reconstruction of verb BLT. It works fine > and gives the expected results. I have inserted it in > http://www.jsoftware.com/jwiki/Doc/Articles/Play171 after the first > mention of BLT. > > I will also include you in the list of those acknowledged in the > production of APWJ Edn 2. > > What follows is not needed for APWJ Edn 2 but interests me nonetheless... > > #BLT 7 > 47293 (...which accords with Gene's figures) > #BLT 8 > |out of memory: BLT > | ~. bl"1(y#y)#:i.y^y > > Gene too says in the paper in question that he can't use BLT beyond 7. > He calculates the space needed for BLT 8 (admittedly by his version) > as 536,870,912 bytes -- say half a GB. But my iMac has 4GB of > installed memory. I would have thought off-hand it would have managed > BLT 8 (though certainly not BLT 9, which would need roughly 14GB by > Gene's calculations). > > What's going on? How much of my 4GB is available for J? ...to malloc > in one go? Or are my integers taking up two/four/eight times the bytes > of Gene's? > > Ian > > > On Wed, Oct 21, 2009 at 11:11 AM, David Mitchell <[email protected]> > wrote: >> Oleg Kobchenko wrote: >>> In the article 24 "Blists in OLEIS" >>> >>> http://www.jsoftware.com/jwiki/Doc/Articles/Play171 >>> >>> the definition of the BLT verb is missing. >>> >>> It is needed to complete the publication of >>> At Play with J. >>> >>> I guess if we should come up with a substitute, >>> it might as well be a best shot. >>> >>> >>> >>> ---------------------------------------------------------------------- >>> For information about J forums see http://www.jsoftware.com/forums.htm >>> >> In the keeping of brute force: >> >> bl =: ] i.~ [: /:~ ~. >> >> BLT=: 3 : 0 >> ~. bl"1 (y#y)#: i.y^y >> ) >> >> -- >> David Mitchell >> ---------------------------------------------------------------------- >> 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
