Electronic dissertations library

Electronic dissertations library

XML::Parser of RSS

I have drunk the XML Kool-aid, also the Perl References Kool-aid.

#!perl -wl
use XML::Parser;
use LWP::Simple;
$content=get("http://earthquake.usgs.gov/recenteqsww/catalogs/eqs1day-M2.5.xml");
my $xml=new XML::Parser(Style => 'Tree');
$f=$xml->parse($content);
exit unless $$f[0] eq 'rss';
@g=&findelement('channel',@$f[1]);
@items=&findelement('item',$g[0]);
for (@items) {
  @s=&findelement('dc:subject',$_);
  die unless @s==2;
  $mag=&intext($s[0]);
  $post=&intext($s[1]);
  $title=&gettext('title',$_);
  $link=&gettext('link',$_);
  $date=&gettext('description',$_);
  print "$title\n$date\n$link\n$mag $post\n";
}
sub findelement {
  my ($tag,$val);  my @ret;  my ($target,$arr)=@_;
  @_=@$arr;
  shift; #throw away attribute hash
  while (@_) {
    $tag=shift;    $val=shift;
    push @ret,$val if ($tag eq $target);
  }
  @ret;
}
sub gettext {
  my ($target,$arr)=@_;
  my @t0=&findelement($target,$arr);
  &intext(@t0);
}
sub intext {
  my @t1=&findelement('0',$_[0]);
  $t1[0];
}

Lossy conversion between decimal to binary

Suppose you have random decimal data, for example decimal digits of pi, and you want random bits. Take 28 digits at a time and get 93 bits out (2^93 = 0.99035e28), rejecting if the value is too large.

For the other direction, take 196 bits at a time and get 59 digits out. 2^196=1.004336e59.

1.66053886 yoctomoles

CODATA Value: atomic mass unit-kilogram relationship

installing athena

Installing Athena on this new machine was a long drawn out process. the bootkit didn't see the motherboard network card, so I borrowed a PCI network card from another machine.

backup /boot /dell /etc /lib/modules/2.4.21-15.EL /usr/X11R6/lib64 /var/lib

backup text of ls -laR, df, rpm -q -a, fdisk p q

I wish I had also backed up rpm --q -a --provides

on partitioning, careful not to blow away the Dell utility partition and the secret reinstall partition. And leave some space for a future operating system partition.

Remember to do advanced custom install to select a multiprocessor kernel.

editing grub and fstab to change hda into sda for this weird SATA is it SCSI or is it not madness.

redhat-config-network to configure the motherboard eth0.

SNOWFLAKE-A-THON

SNOWFLAKE-A-THON

My snowflake entry and source code.

import Complex
import System

type C = Complex(Double)

mandelbrot_eval::Int->C->Int
mandelbrot_eval max_iter c = 
  length 
  $ (takeWhile (\z -> (magnitude z) < 2))
  $ (take max_iter) 
  $ (iterate (\z ->  z*z+c) (0:+0) )

half_width_pixels::Int
half_width_pixels = 400
scaling::Double->Int->Double
scaling width = (* (width
            /(fromIntegral half_width_pixels)))
          . fromIntegral
range::Double->[Double]
range width= map (scaling width)
    [-half_width_pixels .. half_width_pixels]

iterations::Int
iterations = 200

main::IO ()
main = do{
   let {s = show (2*half_width_pixels+1)};
   putStrLn ("P3\n"++s++" "++s++"\n"++"255");
   args <- getArgs;
   let {side = exp(-(read (head args)))};
   putStr $ unlines $ map show
   $ concatMap (  (\i -> [i,i,(i+55)])
                . (mandelbrot_eval iterations)
                . (+ center) )
   $ [x:+y | x<-(range side), y<-(range side)]
}

center::C
center =  0.4245127190 :+ 0.2075302281

dkms nvidia driver rpm installing

So Dell shipped me this new dell machine running RHEL3 with a nvidia (pci express quadro nv 280 mumble something). Having reinstalled (with Athena) the task was to get the nvidia driver working again. Interesting things:

• The rpm they gave me seemed to have been precompiled for 64bit linux.
• It came with version 6624, thought the newest at support.dell.com was 6105
• Whatever that 6105 package was from dell, I regret having tried it

Anyway, the right thing to do was to use /dell/source/dell-nvidia-6624.1dkms.src.rpm. First be root, then rpmbuild --rebuild it, then rpm -Uvh to install the rebuilt rpm. All the proper DKMS stuff gets triggered (because I had installed dkms first).

Twinview works happily as advertised, and I now have 3200x1200 display on two CRTs.

Fun with Internationalized Domain Names

Punycode converter See RFC3490, RFC3491, RFC3492 and RFC3454. For example, fdfd is gay.