Number theory, origami, open-source software
May 14, 2008
After I finished Taxicab(6), Christian Boyer asked me if I could verify the tenth cabtaxi number, for which he knew an upper bound. So I worked on that after finishing the sixth taxicab number. As it turns out, his upper limit was the actual tenth cabtaxi number.
For more details, please go to my Ramanujan numbers page.
March 9, 2008
I have been working for a while now on finding or verifying the sixth taxicab number. The number above, 24153319581254312065344, has been known since 2002 as an upper limit and a probable candidate for the sixth taxicab number, but it was not known whether it was actually itself Ta(6). I have recently completed a scan of the range [1e21 .. 2.4153e22] (the range [1 .. 1e21] had already been examined by others and found to not contain Ta(6)) and have verified that 24153319581254312065344 is indeed Ta(6).
For more details, please go to www.korgwal.com/ramanujan/.
I have lately become interested in learning the functional programming language Haskell. This is a significantly different beast than the stuff I've mostly dealt with, so it's been kind of tricky. I found a most excellent tutorial which describes and develops a real and interesting program, an interpreter for a sub-set of Scheme (another programming language, for those of you who are not lisperati). I went through and beyond that tutorial, and the results (so far) of my play are here: haskeem, a scheme interpreter in haskell.
In addition, I've since written more stuff in haskell... here is
umm, a
tiny minimalist command-line accounting program in the style of
ledger
and its haskell remix
hledger.
Here are the origami models which I've made; here is a version of the page with smaller pictures, if you have a slow connection or a small screen.
A couple of other pages, for some more-specialized things I've done:
| Copper-mesh Horse | 2007-04-22 |
| Flying Unicorn in stainless mesh | 2007-04-22 |
| Flying Unicorn | 2007-01-27 |
| KNL Dragon | 2007-01-14 |
| Leaping Guitarist | 2007-01-14 |
| Red Fox | 2007-01-14 |
| Dancing Shiva | 2007-01-14 |
| Beaver | 2007-01-14 |
I have lately become interested in playing the flute; specifically, I got the 302B models of soprano and alto recorders by Yamaha, which are plastic but sound pretty nice and are nicely affordable, about $20 and $30, respectively; I got them at Musician's Friend (no affiliation except as a satisfied customer). I've made up a fingering chart (for the soprano recorder only so far) and some blank sheet music graph paper. Both of these are postscript files, both are tiny (a few KB). Enjoy!
And here's something completely different: a few years ago I was a member of a small investment club, and this is some software which I used to do the monthly record-keeping and reporting. Warning: for geeks only! You'd better be comfortable with perl and TEX if you want to use this stuff... here you go! It's all released under the GPL.
Another something completely different: sscoop, a program to crawl through a scoop-based web site, downloading stories and comments into a local database for off-line reading or presentation in a different format. note: this has only been tested (by me) against ip-wars.net.
If you have questions or comments about the stuff here, please contact me at korg@korgwal.com.
Enjoy! -- Uwe Hollerbach
Page last modified at 2008/05/25 11:00 US/Pacific