Analysis center, .NET and LSA project

Today I was testing a new analysis center for Effektor and we ran into some issues with different DLL version numbers. I learned about the GAC which is a piece of .NET CLI that maintains various DLL's using strongly typed names. You can access the GAC through the normal filesystem in %windir%\Assembly but you will only see a shadow, since normal FAT32 does not support files with the same name. The GAC is able to used the strongly typed names to find the correct version of a DLL for a program, thus avoiding DLL HELL.

As promised I added the LSA project to my open bitbucket repos.

Streaming to a MediaElement in C# Windows 8 Apps

Today I learned that things can be too easy sometimes :) I was trying to set the source of a media element to an .mp3 stream from DR. I tried all sorts of tricks to convert a URI to a StorageFile to a stream. After some hours of this I stumbled upon the solution:

mymediaelement.Source = new Uri("Address");

KISS

Stemmer

Today I did a danish Stemmer in C#. I will put it on my bitbucket asap. It is an implementation of the algorithm foud here: http://snowball.tartarus.org/algorithms/danish/stemmer.html. I plan to continue the project into a full LSA machine in time. I also saw a strange bug in telerik grids where calling get_selecteditems() returned a null the first time being called after loading a page, but first getting the mastertable, and then calling get_selecteditems() on that, got the correct items. A very annoying bug.

More buttons and strings in Effektor

Today I fixed some wrong strings and corrected a small mistake in some button-activation javascript in effektor. It really didn't teach me anything, perhaps that it's better to proof-read and slow down than having to go back and correct text later. I also printed some text on Bloom Filters which is a datastructure I am looking into for my thesis. I had my first meeting with Rasmus Pagh yesterday and he suggested this topic, so I will try to give it a shot, it sounded rather interesting.

Fermats last sentence

Today I had time for some leisure reading. I recently got Fermats Last Theorem by Simon Singh. It's a pleasure to read, I do feel that it's really lacking in sources especially in the stories about Pythogoras which is told in (uncredible?) detail. But some of them are interesting enough. I learned the Pythogoras sentenced Hippasus to drowing because he discoverede the irrational number sqrt(2) which was considered some kind of heresy. I think the stories retold by Simon Singh are taken from Pythagoras: His Life, Teaching and Influence by Christoph Riedweg and found some online debate that indicate that they are not really well supported. I learned the concepts of the theorem, but it's annoying that the book is not more critical of its sources.

Matematical analysis and linear algebra

Today I passed my exam in Mathimatical Analysis and Linear Algebra (again). The exam was on linear systems and I was told that I should have spend less time on basic topics and move to more advanced topics faster. The subject was very basic though and the examiner (Dan Witzner) and censor did not really push me for more advanced topics so I was a bit diasppointed in that feedback. I also got scolded for not answering all questions but the only question I didn't specifally adress was matrix multiplication which I had already coverede in depth.

I can't complain about the grade so I wont, but to try and learn something from it I will say that I learned that when going for a math exam it's enough to just mention the execistens of some property and only proof it when asked specifically for a proof. I think this also confused me since my math courses at Aarhus University  where focused on proofs.

CORES2013 and exam prep.

It has been very quiet here for a while since I have been preparing for my exams and attending CORES2013. Today I hope I can return to my daily 10 minutes. Today I learned how to properly construct the single value decomposition of a matrix. A=UEV:

U = { U1 U2}

U1 is an ortonormal basis for R(A)

U2 is an ortonormal basis for N(A^t)

E = {(E_1,0)^t,(0,0)^t}

Where E_1 contains single values aka. the squareroots of the non-zero egienvectors along the diagonal.

V={V_1^t, V_2^t}^t

V_1 is an ortonormal basis for C(A)

V_2 is an orthnormal basis for N(A)