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00:05:02 <slereah__> Are Schönhage's machines easier to understand than Kolmogorov's?
00:15:16 <slereah__> Problem is, I can't find anywhere in his article an example that doesn't involve the graph itself!
00:15:40 <slereah__> The only example is "How to double the graph".
00:16:06 <slereah__> Not a whole lot helpful for a more useful algorithm.
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19:19:03 <ais523> why isn't one's complement used more often?
19:19:20 <ais523> it's easy to create a two's complement system by just using unsigned adders and disregarding the carry
19:19:40 <ais523> but looping the carry from the msb round to the carry input of the lsb gives you ones' complement
19:20:01 <ais523> (albeit with -0 being the standard representation of 0 and +0 being impossible to get unless you start a number at that value)
19:20:32 <ais523> one big advantage is that if you use the right number of bits, you can make the number of available integers a prime
19:20:40 <ais523> so that multiplication is completely reversible
19:22:50 <ais523> hmm... my rant about 1's complement doesn't seem to have sparked off a discussion yet
19:23:50 <slereah_> Well, I don't know if the others are here, and I don't know what's 1's complement.
19:24:13 <ais523> most computers represent negative numbers using 2's complement
19:24:38 <ais523> given that you're storing numbers in binary (unless you're using TriINTERCAL or Malbolge, this is likely), and that you have a fixed number of bits (i.e. not a bignum)
19:24:56 <ais523> then you form the 2's complement of a number by changing all 0s to 1s in the number and 1s to 0s, and then adding 1
19:25:03 <ais523> 1's complement is the same except that you don't add the 1
19:25:40 <ais523> the advantage of 2's complement, which is the reason it's so commonly used, is that signed and unsigned arithmetic work the same way; for signed arithmetic, you just disregard the carry
19:25:43 <slereah_> Wouldn't you have problems differentiation between, say, -1 and 255?
19:26:01 <ais523> with an 8-bit system, you'd generally range from -127 to +127
19:26:22 <ais523> 2's complement would go from -128 to +127
19:26:42 <ais523> (1's complement has two sorts of zero, which act identically, but can be confusing to someone used to how arithmetic normally works)
19:27:07 <ais523> They're normally referred to as +0 and -0, but both act like 0 with respect to all the usual arithmetic operations
19:28:42 <ais523> the real interest comes when the number of bits you use is not a power of 2
19:28:49 <ais523> (to be precise, when 2^n-1 is a prime)
19:29:05 <ais523> because then multiplication by any integer except 0 maps all integers onto unique integers
19:29:38 <ais523> and it's almost as easy to implement in hardware as 2's complement (at least in terms of wiring)
19:29:50 <ais523> it's slower on average, but the worst-case response time is the same
19:31:29 <ais523> more elegant maths IMO
19:31:50 <ais523> oh, and you can pick one of the zeros to use as 0 and the other one to detect uninitialised data
19:33:59 <slereah_> "More difficult to understand quite unlike a "computer" -- abstract or otherwise."
19:34:51 <ais523> what are you referring to?
19:35:40 <slereah_> It's from the wiki article on pointers machines.
19:38:51 <slereah_> It seems to be one of the most obscure computing method.
19:39:54 <ais523> I had a vague memory that such things existed
19:39:59 <ais523> but don't really understand them
19:40:40 <slereah_> Is there anything based on it?
19:40:58 <slereah_> It would be nice to have a concrete example.
19:44:29 <ais523> after reading a few Google links I think I understand what's happening to some extent now
19:45:53 <ais523> basically, at any given point the memory is a graph, with nodes connected to each other by directed coloured edges
19:46:24 <slereah_> Though they don't have to be directed apparently.
19:46:38 <ais523> and at each step, there are replacement rules, such as 'if a node is connected to another node via a red edge and then a blue edge, add a green edge pointing to that node from the original node'
19:46:55 <ais523> hmm... maybe not quite like that, I still don't understand them properly
19:47:12 <slereah_> I understand roughly how it works.
19:47:26 <slereah_> Proble is, I don't get much how it computes.
19:47:33 <ais523> that's usual with esolangs
19:47:50 <slereah_> None of the examples are using problems outside of the graph itself.
19:47:51 <ais523> one of the articles said that you could make a cellular automaton by connecting the original graph up as a grid
19:49:31 <slereah_> There's an example that's sort of useful, though not that clear.
19:49:47 <slereah_> It shows how to do a list of integers.
19:50:38 <slereah_> "On the definition of an algorithm", by Andrei Kolmogorov and Uspenskii.
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19:51:38 <slereah_> Though the Kolmogorov definition adds some strange conditions, like every nodes must have a type and a node can't be connected to two identical types.
19:52:28 <slereah_> So there's a lot of nodes type 2-3-4-2-3-4-2-3-4... because of it.
19:52:42 <slereah_> (0 is the starting node type and 1 ending type)
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20:17:11 <SimonRC> though best run with emacs -batch -l dunnet
20:19:01 <Sgeo> There's minigolf in movie 4
20:20:00 <Sgeo> Futurama movie
20:20:31 <Sgeo> wrong chan basically
20:20:35 <slereah_> Well, it's Futurama, so probably!
20:29:26 <ais523> SimonRC: ever tried Lost Kingdoms?
20:29:31 <ais523> I'm stuck on the wildcat
20:30:30 <ais523> I mentioned this to ehird, and wrote a serialising BF interp so that I could send a save file, but ehird couldn't solve that bit either
20:43:47 <SimonRC> wasn't it originally written in bfbasic?
20:45:19 <ais523> there are two versions
20:45:22 <ais523> the original was in BASIC
20:45:33 <ais523> an improved version was written in BFBASIC and compiled to BF
20:45:50 <SimonRC> is there any bfbasic source?
20:46:27 <ais523> even the original BASIC source is in binary
20:46:40 <ais523> I suppose you could try decompiling, because BFBASIC itself is open-source
20:46:55 <ais523> but someone would have to write a decompiler first
20:48:03 <SimonRC> the actual page only says that the original LK was written in bbc basic and translated to brainfuck...
20:48:11 <SimonRC> it doesn't say anything about bfbasic
20:48:47 <ais523> it did use BFBASIC, though, I'm pretty sure of it
20:49:04 <ais523> especially because the patterns at the end of the source are characteristic of it
20:50:59 <ais523> FWIW, Esolang's entry on Brainfuck states that BFBASIC was used
20:51:09 <SimonRC> but that's the only source I can find
20:51:20 <SimonRC> apart from various translations of it
20:52:28 <ais523> there aren't many mentions of that game on the Internet anyway, for some reason
20:53:09 <ais523> also, note the mention of Jeffry Johnston in the credits at the bottom of its page
20:53:32 <ais523> Jeffry Johnston created BFBASIC, and it also has contributions by Jon Ripley, which would seem to make the situation even more likely
20:54:03 <SimonRC> though the bf world is quite small isn't it?
20:54:31 <ais523> not as small as the rest of the esolang world
20:54:35 <slereah_> It's the biggest communauty in esolangs !
20:54:54 <slereah_> Though I wonder if Intercal isn't used more.
20:55:08 <SimonRC> comp.lang.intercal has com activity
20:55:12 <ais523> INTERCAL is probably used a lot
20:55:19 <ais523> and don't you mean alt.lang.intercal
20:55:23 <ais523> or are there really two newsgroups?
20:55:49 <slereah_> Well, I wouldn't go as far as "lot".
20:56:01 <ais523> (apparently ~50 Debian users who send popularity contest stats installed C-INTERCAL, ~30 installed CLC-INTERCAL, single-figures > 1 actually use them)
20:57:06 <ais523> latest stats from http://qa.debian.org/popcon.php?package=intercal are that 4 people used C-INTERCAL recently
20:57:31 <ais523> (bear in mind that this is restricted to Debian Linux users with popularity stats turned on, so the true number is likely much higher)
20:57:49 <ais523> and 3 used CLC-INTERCAL
20:58:03 <ais523> either the total installed numbers have gone down, though, or my memory of them was wrong
20:58:51 <ais523> oh, add one to the C-INTERCAL stats for me, because although I use Ubuntu, I don't have C-INTERCAL installed from packages as I'm the maintainer and have my own newer test versions
21:01:11 <ais523> (I do show up on the CLC-INTERCAL stats, I think)
21:01:59 <RodgerTheGreat> I really think lightning-fast mental math is neat: http://www.ted.com/index.php/talks/view/id/199
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21:05:21 <ais523> no double quotes, so that was a server-generated quit message
21:05:29 <ais523> (presumably a case of errno=0 but an error happened anyway)
21:05:41 <ais523> I came across a program recently which was exiting with "success" as the error message
21:05:49 <ais523> because it was using perror but nothing had set errno
21:06:17 <ais523> (apparently on that system mmap doesn't always set errno on failure)
21:06:20 <SimonRC> that video seems to have no image
21:06:56 <SimonRC> is there supposed to be one?
21:07:25 <ais523> SimonRC: I don't understand what you're trying to say, can I have some context or did you type into the wrong channel?
21:07:38 <SimonRC> the video that RodgerTheGreat posted
21:07:42 <ais523> ah, you're referring to RodgerTheGreat's comment
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21:13:01 <SimonRC> ah, the "missing digit" one is via casting out nines, I suspect
21:14:02 <SimonRC> and the previous ones are simplified by knowing your times tables up to 100
21:15:32 * SimonRC tries to recall the Lewis Caroll technique for finding the day of the week of a date.
21:18:33 <SimonRC> ah, yes, he is using his tables up to 100
21:19:16 <SimonRC> ooh, nice memorisation hack
21:20:18 <RodgerTheGreat> pretty simple techniques, he simply applies them with tremendous speed and accuracy
21:21:57 <RodgerTheGreat> this is the same kind of thing: http://www.youtube.com/watch?v=wIiDomlEjJw
21:23:24 <SimonRC> otoh, see the tale of richard feynmann and the abacus-seller
21:26:22 <SimonRC> erm, in the book "Surely You're Joking Mr Feynmann"
21:28:37 <ais523> it's a good book, but the sequel is much worse
21:28:50 <ais523> (I can't remember what the sequel is called)
21:28:58 <ais523> (probably because it wasn't very good)
21:52:44 <SimonRC> wow: http://www.pdp8.net/sound/sound.shtml
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