January 22nd, 2008

Completely needless and trivial - my own implementation of fft (fast fourier transformation) in matlab. Yes, I know, there ist already fft, fft2, and fftn - but as a proof of concept:
function myfft(vec)
%MYFFT My own simple version of FFT
vec * fftmatrix(length(vec))
end
function thematrix = fftmatrix(n)
% FFTMATRIX Generates a fft-matrix of the size n x n
thematrix = zeros(n,n);
for izeile = 1:n
for ispalte = 1:n
thematrix(izeile,ispalte) = exp(i*(2*pi/n))^((izeile-1)*(ispalte-1));
end
end
end
Posted in maths | 1 Comment »
December 19th, 2007

Am 6. Dezember 07 hat der Nationalrat gegen Mitternacht, ohne die sonst üblichen Beratungen in den Ausschüssen, ein neues Sicherheitspolizeigesetz beschlossen.
Somit ist die Polizei befugt, ohne richterliche Genehmigung, u.a. Standortdaten von Handies und dynamische IP-Adressen bei den Betreibern einzuholen, ohne wenn und aber…
Das sind wohl die nötigen Vorbereitungen, um die richtigen Werkzeuge zur effektiven Nutzung der Vorratsdatenspeicherung, zu haben. Gleich mal alle Bürger unter Generalverdacht stellen.
Die Grünen haben eine Petition im Netz gestaltet, um zumindest die sonst üblichen Vorberatungen zu solchen Gesetzen einzufordern.
Posted in politik | No Comments »
December 16th, 2007

Yesterday I’ve got mail from the amazon developer-service (I am a user of amazon s3) about their upcoming feature, also /. has a story about it.
Sounds interesting - building web applications and using amazon’s database (a store where you can create/update und delete objects) as persistence.
More and more applications and services seem to make a shift from traditional SQL/DBMS to object-stores. One of these ideas, I would be interested most, is Allegro Cache - a lisp persistence system for CLOS objects - sadly not free but part of ACL. In the opensource-community there exists elephant and rucksack. Exspecially rucksack seems to be a very interesting stuff, unfortunately in early alpha-state. Elephant depends on BerkleyDB but has the option of alternative backends.
Posted in database, lisp | No Comments »
December 15th, 2007

All about Linux: Bash Shell Shortcuts - I am working now for around 14 year with linux/bsd and basically with bash as my favorite shell, on the other hand I am addicted to emacs, the one and only true editor/os. And I haven’t realized, that I can use so many emacs-keybindings in bash… I’ve known of course of ctrl-a, ctrl-e - but alt-t or alt-l - that’s good new news! Also mentioned in this entry.
Posted in emacs | No Comments »
December 9th, 2007

A very interesting topic, exspecially as many frameworks (f.e. ruby on rails) tend to produce automatically surrogate keys. Lee Richardson tries to advocate surrogate keys in his blog-post. I hate surrogate keys, often calling people using them “M$-Access-Users”. But, to be honest, sometimes, exspecially when mapping OOP-Classes into tables, there is no other way. Best answer to Lee’s post seems to be Ian Batty’s comment. Let me cite one paragraph:
“Personally I am a natural key guy. Saying that, and this is where your example loses credibility, practical experience has shown that for a person there is no natural key, so I create a surrogate. However, if I am creating an entity that has a true unique identifier, that doesn’t change and meets all the other requirements then I will use it.”
Seems to be a very good general advice.
Posted in database, postgresql, ruby, lisp | No Comments »
December 8th, 2007
Posted in Uncategorized | No Comments »
December 3rd, 2007

Sounds interesting, Gary King shows in his blog, and cites others, there is an interesting alternative to abcl: clojure. A lisp implementation running in java virtual machine. At least not Common Lisp, but a kind of scheme (it is a lisp-1) with interesting aspects. F.e. mighty lists being inheritable and easy connectors to the java-world.
Posted in lisp | No Comments »
November 17th, 2007
… nicht mal richtige GFX und auch kein gutes Aussehen. Spaß beiseite - beeindruckend welch cooles 3D-Werkzeug damals auf einer Symbolics Lispmaschine lief… Schade, warum gibt es die Dinger nicht mehr…
Posted in nostalgie, lisp | No Comments »
October 22nd, 2007
Ein Laserschwert oder doch ein iBook? Grandiose Applikation, die aus einem iBook oder Powerbook mittels des Sudden Motion Sensors ein Laserschwert macht. Wirkt insbesondere bei Besprechungen….
Posted in mac | No Comments »
September 28th, 2007
Slime wird momentan komplett umgemodelt. Zusatzfuntionalitäten kommen in Module, der “eigentliche” Slime beinhaltet nur mehr die Grundfunktionalitäten.
D.h. auch das Setup in .emacs muss dementsprechend adaptiert werden - ist leider noch nichts so richtig dokumentiert. Bill Clementson hat hier eine gute Zusammenfassung geschrieben! Spread the Info…
Posted in emacs, lisp | No Comments »