Recent blog entries for rkarl

22 Nov 2004 (updated 22 Nov 2004 at 17:30 UTC) »

Took another wack at some semi-Lagrangian Navier-Stokes code thats I abaondoned some time back. Basically, it worked, but I never bothered to make the LHS symmetric. Instead, being lazy, I just solved with BiCGSTAB_l.

So, after a few really stupid errors, it now works again, solving with conjugate gradients. Unfortunatly, the bloody thing now takes forever to converge. Arg! Guess this means that I have to write preconditioning code. Oof.

It is some consolation that now, at least, each iteration is about 3x as fast

18 Nov 2004 (updated 18 Nov 2004 at 18:09 UTC) »

To procrastinate working further on thesis type stuff, I've been playing with graph drawing a bit, also thanks in part to some taunting by an officemate.

I guess its not a total wash, as I need some code for MDS anyway; maybe this can be written off as a debugging project.

Anyhow, in case anyone is interested, there is a binary tree, another view of the same tree, and a grid with connected corners

8 Oct 2003 (updated 8 Oct 2003 at 00:46 UTC) »

mmmmm LaTeX. I wonder what was the major motivating factor for various people getting hooked on LaTeX. I got hooked while writing physics lab reports full of equations and derivartions. Now I cringe at the thought of having to put together a bibliography without bibtex, let alone try to get figure references right.

I'll also admin to being a LyX fiend. I may have been using it a bit too much; I had to put together a group report the other day, at home, sans LyX.. and I help having to look commands up. doh!

I try to jab at my friends studing things like communications at their reliance on thing like word, and how pales to LaTeX. They usually fire back with how not-gui-ish it is; Oh well.


I've been meaning to try and check up on that disc to see if it was any good; I guess its time for a cd store spending spree. Its only debt...


What do the IT folks there with 'depreciated' hardware? There must be a big storage someplace here, because folks are forever replacing machines, and the old ones never show up in the trash. When I did my undergrad, the IT dept would put old or dead hardware outside their building for the trash people to collect. Many an evening were spent trying to get old macs to boot.. Anyhow, if there is a mass grave for hardware nearby, might be able to 'acquire' a machine for 'research'. Finding a laptop might be difficult, but you could probably assemble enough parts for a functional desktop..

Have to give a presentation tomarrow, basically improvements on a previous presentation [The old one was about a paper on pulling mattes with principal component analysis; this one is about the same, but with robust PCA]. No motivation to make slides.. Hopefully I can reuse most of them.
5 Sep 2003 (updated 5 Sep 2003 at 16:40 UTC) »
dhess, jdybnis:

In the case of a really bogged down system with plenty of piggy processes, I wonder if at some point it becomes acceptable to block on a allocation request for some given time, to see if anyone gives up their slot at the feeding line..

Oof. Spent yesterday cleaning bottles scavanged from the recycling center. I made a royal mess on the floor, dumping plenty of water on it accidently.. Oh well, I guess its clean(er) now that it was before. Someone suggested adding some baking soda to water for soaking bottles to loosen up the labels. But, the didn't really say how much to use. So, very scientifically, I dumped a few generous pinches into the pot that some bottles are currently soaking. We'll see if that does any good..

3 Sep 2003 (updated 3 Sep 2003 at 15:22 UTC) »


I miss zines. I miss rummaging through a pile of warn paper from some lonesome backroom copier.

I also miss having time to poke around at recent developments in graphics. Wandering through journals and web pages is fun, making pretty pictures perhaps even more so. Why are there always so few free hours in the day for fun stuff?! arg!

So, I'm half comtemplating putting together a graphics related newsletter. But wait, aren't there already tons of graphics tech/news/code/whatnot sites out there? Sure, but a majority of them have a heavy focus on realtime applications (e.g. gamasutra, gamedev, flipcode, The good ol Raytracing News was tons of fun, but long times between updates doesn't do well for the fiending folks..

Most likely nobody would read such a thing, but who cares..

wiggly -

A Catmull-Rom Spline might do what you want..

Is there an easy way to get ahold of the geometry defining font glyphs [ie can it be snatched from freetype, or easily parsed out of a file] for your favorate type of font?
I'm toying around in my head with a [limited] postscript interpreter which uses GL to render (or perhaps such a beast already exists?). It would make for great presentations when fed through chromium on a display wall. It doesn't seem that difficult, save for font rendering...

salmoni-the Lyx spell check spits out a word count after it has finished the document.. Somewhat backwards I guess, but if you _must_ have word counts :)
so, it only took an afternoon for it to dawn on me that i should install a new kernel to get the 1394 stuff to work. sure enough, it behaved much nicer afterwards.

camera seems to be doing well, execept the lens has some serious radial distortions going on. ended up spending friday trying to compensate for them. it's not quite there yet; i'm still using a fixed center and was too lazy to write the 5 lines to do interpolation, but it is looking better.

i need a wort chiller. though, waiting for it to cool does give me a good excuse to do laundry and catch up on diary entries

tomarrow is the day of seminars.. all morning long. eug.

probably will try and get a 1394 board up in the afternoon, so i'll have a camera to start playing with projector alignment. pretty neat idea. if you can determine how your projector is aligned with respect to its display (given a sane display surface..) you can invert the transform, plop it on your matrix stack, and poof. a corrected display.

whats that?

added some cheesie fonts and tooltips to my graph editor.. its almost time to make it do something useful.

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