R J Cano on Thu, 20 Apr 2017 04:38:22 +0200 |
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Re: 4 Gigabytes of RAM are not enough! |
Hi Bill!, Merci, about malining lists. Sure, no problem. Cheers, Remy 2017-04-19 14:13 GMT-05:00, Bill Allombert <Bill.Allombert@math.u-bordeaux.fr>: > On Wed, Apr 19, 2017 at 05:01:28AM -0400, R J Cano wrote: >> Greetings, >> >> This time featuring a problem that seems to be a RAM-memory's pacman >> monster... >> >> Briefly: If you are looking for arbitrary symmetric/antisymmetric >> patterns inside the first N!-1 terms of oeis.org A217626, ...for N>6 >> the problem becomes (yet inclusive if having a very simple and >> efficient script!) intractable due there is no enough RAM to complete >> the corresponding report... >> >> Attached to this mail comes a PARI/GP script which can be used to >> appreciate that issue. >> >> The usage is simple, load it and set: >> >> p=vecDiff(A217626_vec_1(7)); >> >> then run the following search&report: >> >> q=Patterns(p,1,5,1); >> >> Which tells Patterns( ) to search for any pattern of size 5, and >> exclusively (e=1) size 5, >> >> For example the pattern [1,9,2,9,1] or the first 3!-1 terms of A217626 >> should be present (7-3+1)! = 120 times; However: The execution crashes >> before allowing us to verify that!!, giving up due lacking of stack. > > The problem is that the output of Patterns is too large to fit > in the memory, this is not a problem with the algorithm: > > ? p=vecDiff(A217626_vec_1(6)); > ? q=Patterns(p,1,5,1); > ? sizebyte(q) > %15 = 1998476512 > > so q is almost 2GB. You need to find a more compact representation for > the output of Patterns if you want to go farther > > Cheers, > Bill. > > PS: please avoid crossposting between pari-dev and pari-users, a lot of > people are subscribed to both lists and so receive it twice. >