ls -lart Projects && remember

[fivemack]

that it is not the beginning of the work, but the continuation thereof until it be thoroughly finished, that yieldeth the true glory

[which I remember as a commonly-used prayer at school, but cannot find through Google; on the other hand, of all the organisations of the Earth, my secondary school is among those whose possession of a totally independent prayer-book would be considered least surprising]

drwxr-xr-x     4 tom  tom    136 Feb  4  2005 mandy
drwxrwxrwx    11 tom  tom    374 Feb  6  2005 Spheres in a cube
drwxrwxrwx   286 tom  tom   9724 Feb  6  2005 FRACTREE
drwxr-xr-x    12 tom  tom    408 Feb 11  2005 fixedprec
drwxr-xr-x    16 tom  tom    544 Mar 15  2005 random_graph
drwxr-xr-x     6 tom  tom    204 Mar 17  2005 enceladus
drwxrwxrwx    31 tom  tom   1054 Mar 17  2005 orbital
drwxr-xr-x    68 tom  tom   2312 Mar 25  2005 srtm
drwxr-xr-x    31 tom  tom   1054 Mar 31  2005 pentagon
drwxr-xr-x    15 tom  tom    510 Apr 19 19:55 crt-fft
drwxr-xr-x    18 tom  tom    612 Apr 19 21:17 primestrings
drwxr-xr-x    15 tom  tom    510 Apr 25 21:42 irreducible
drwxr-xr-x     7 tom  tom    238 May  2 22:36 streetmap
drwxrwxrwx    24 tom  tom    816 Jun  3 21:08 repel
drwxr-xr-x    64 tom  tom   2176 Jun 13 19:09 optbin
drwxr-xr-x     7 tom  tom    238 Jun 19 19:19 mmxsort
drwxr-xr-x    12 tom  tom    408 Jun 23 21:08 eurcit
drwxr-xr-x    13 tom  tom    442 Jun 23 23:09 demographic
drwxr-xr-x    10 tom  tom    340 Jun 29 10:10 smallres
drwxr-xr-x     7 tom  tom    238 Jun 29 11:34 squareful
drwxr-xr-x     9 tom  tom    306 Aug  1 19:40 connected
-rw-r--r--     1 tom  tom   1276 Aug 14 11:12 ling.cpp
-rwxr-xr-x     1 tom  tom  29160 Aug 14 14:33 a.out
-rw-r--r--     1 tom  tom   1769 Aug 14 14:34 ling2.cpp
drwxr-xr-x    41 tom  tom   1394 Aug 22 23:18 haskell_stuff
drwxr-xr-x     8 tom  tom    272 Sep 15 19:59 primefilt
drwxr-xr-x    21 tom  tom    714 Sep 28 23:25 kylix
drwxr-xr-x     8 tom  tom    272 Oct  8 22:22 dudcc
drwxr-xr-x    28 tom  tom    952 Oct 12 00:42 diffeq

Not one of them even close to finished, though I can remember nearly all of their goals; and there are more on the other computer. Some I've worked at intensely for one evening, some for a week of evenings; I don't know how many of them would take much more than a month of evenings to complete, or be worth the effort once completed.

Comments

[fivemack.livejournal.com]

Error-correcting codes are what you get if your model of failures is 'I transmit down this wire, and sometimes what comes out isn't what's sent, but I can't tell where the errors are'.

There's also a failure model 'I have N hard discs; sometimes, when I turn the computer on, some of these hard discs will have decided to depart and contemplate their inner doorstop; you can recognise which ones have done this by the grinding noise'. I was trying to figure out useful encodings for that case (something like RAID5, but able to handle two or three disc failures); DudCorrectingCode rather than ErrorCorrectingCode.

Cycling to work this morning, I realised that correcting N errors was equivalent to surviving 2N disc failures [for N errors, you want the encodings of different messages to be at least 2N+1 bits apart; for M failures, you need only M+1 differences], so I'd just be re-inventing Hamming codes.

The only moderately interesting observation was that, if you just start at 00000 and count up, writing down the first thing you come to that differs in the right number of places from everything else you've written down, the bits of the result seem always to be linear functions of the bits you're trying to encode.

[jojomojo.livejournal.com]

Ahhh - I was thinking you were writing your own C compiler :)