Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.programming > #6643

Re: generating permutations

Path csiph.com!news.swapon.de!eternal-september.org!feeder.eternal-september.org!mx02.eternal-september.org!.POSTED!not-for-mail
From Ben Bacarisse <ben.usenet@bsb.me.uk>
Newsgroups comp.programming
Subject Re: generating permutations
Date Sun, 22 May 2016 22:58:55 +0100
Organization A noiseless patient Spider
Lines 20
Message-ID <87vb25sqjk.fsf@bsb.me.uk> (permalink)
References <86298170-5592-40fa-a275-7e90d472e2ce@googlegroups.com> <6d8de1c0-c835-4a67-b115-25249177e717@googlegroups.com> <ad4f7ce6-2699-42e3-815e-3ccce7c0200c@googlegroups.com>
Mime-Version 1.0
Content-Type text/plain
Injection-Info mx02.eternal-september.org; posting-host="017616aa25f81ec581c44d76d61ba2f3"; logging-data="1023"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX18R9bB098A9eD18UB+FtMYTeTQxAJE0Z8k="
Cancel-Lock sha1:ThMzwgtCGwVOqUltq/01m/b6Sn0= sha1:2mDNepXePFOGXXXRM8vstr8Qj8g=
X-BSB-Auth 1.43f019f091300e9655b5.20160522225855BST.87vb25sqjk.fsf@bsb.me.uk
Xref csiph.com comp.programming:6643

Show key headers only | View raw

luser droog <mijoryx@yahoo.com> writes:
<snip>
> [...] But an array
> is implemented with a hefty 'dope vector' or descriptor or display which
> allow simple slicing to still share the original data through a modified
> descriptor. The result will still be rectangular, but is no longer bound
> by the linear mapping of the generalized indexing formula. The descriptor
> will be augmented with extra index-transformation powers.

Yes, surely a slice (like yours at least) is just an array whose indexes
go through a table first?  And it seems possible (at first glance) that
you could implement this table as one of your unsliced array objects.
This might be slow for something or memory hungry for others (which it
why some languages have a more constrained notion of a slice) but often
the best plan is to implement something and see if indeed suits your
purpose.

<snip>
-- 
Ben.

Back to comp.programming | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

generating permutations luser droog <mijoryx@yahoo.com> - 2016-05-22 02:46 -0700
  Re: generating permutations bart4858@gmail.com - 2016-05-22 05:36 -0700
    Re: generating permutations luser droog <mijoryx@yahoo.com> - 2016-05-22 14:40 -0700
      Re: generating permutations Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-05-22 22:58 +0100
      Re: generating permutations BartC <bc@freeuk.com> - 2016-05-23 14:09 +0100
        Re: generating permutations luser droog <mijoryx@yahoo.com> - 2016-05-23 21:36 -0700
          Re: generating permutations BartC <bc@freeuk.com> - 2016-05-24 12:56 +0100
            Re: generating permutations luser droog <mijoryx@yahoo.com> - 2016-05-25 19:03 -0700
              Re: generating permutations BartC <bc@freeuk.com> - 2016-05-26 13:08 +0100
                Re: generating permutations luser droog <mijoryx@yahoo.com> - 2016-05-26 08:35 -0700

csiph-web