Lx=d: SundayResearch

``The Kyougen oferrors まちがいの狂言'', 高橋康也, 理想社 What If the comedy of errors in Kyougen?  This is fantastic. ``The Deadline'', Tom DeMarco, 伊豆原弓 訳 This book is formed as a novel. This makes the management effect more vividly. This is Fun and this also makes me think. 世界の測量 (Die Vermessung Der Welt), Daniel Kehlmann, 瀬川裕司 訳 I felt now I know Gauss and Humboldt as people near by. Of course this is an illusion, but I like this.

Gilbert Strang's book, Introduction to Linear Algebra 4th ed., chapter 2 section 5, problem 34 and 45 are following. I think Problem 45 is an extension of Problem 34. Problem 45 is to find the S after this. Then, we could naturally extends this problem to the next: 45' Elimination for a 2 by 2 block matrix : Find inverse of 2 by 2 block matrix. I try to find the solution of this problem here. First, I would like to demonstrate the Equation (1) is not correct in the block matrix. (This is correct when the elements are scalars.) There is a question that how 1/(AD-BC) is defined since A,B,C, and D are all matrices. Isn't it 1/|AD-BC|? But this doesn't matter anyway. Because, Equation (2)'s element 1,2 is DB-BD != 0, element 2,1 is -CA+AC != 0. This comes from the matrix multiplication is not commutative. This means these are non zero element, however, this should be zero. Therefore, Equation(1) is not correct. Many of the relationships held in (scalar) ma...

Sometimes I make Kirie (cutting peper picture). I gave most of them to some friends. This is one of the recent my kirie. I thank Claudia for giving me a permission to put my Kirie's picture in my blog. I translated a poem, "Sen no Kaze ni natte" (Original English "Do not stand at my grave and weep") to German from Japanese.  Why did I translate it based on non-original poem? Hum, I thought I could sing it since Japanese poem has a song. But, it is difficult, of course. --- Tausend Winde (Stehe nicht vor meinem Grab und weine) Englisch Autor: Unbekannte (oder Mary Elizabeth Frye) Japanische Übersetzen: 新井満 (Arai Man) Deutsche Übersetzen: Hitoshi und Leo Stehe nicht vor meinem Grab und weine. Ich bin nicht dort, ich schlafe nicht. Ich bin tausend Winde, die im Himmel wehen. Ich bin der gänzende Diamant auf dem Schnee. Ich bin der Sonnenstrahl auf reifem Getreide. Am Morgen werde ich ein friedlicher Vogel der Dich aufweckt, im kreisenden Flug. In d...

Here is the source code of wc2010.rb. #! /usr/bin/ruby # # World Cup 2010 point simulator # Copyright (C) 2010 Yamauchi Hitoshi # License: new BSD. #------------------------------------------------------------ require "getoptlong.rb" WC2010      = "0.0.0" MAX_MATCHES = 64 #------------------------------------------------------------ # class Wc2010 #------------------------------------------------------------ class Wc2010   # constructor   def initialize()     # last year's result as probability distribution function     @sample = [                4, 2,    0, 2,    1, 0,    0, 0,    2, 1,                0, 1,    3, 1,    0, 1,    3, 1,    0, 3, ...

One of my friends suggested us to predict the world cup points. However, I have no idea. Then I decided to write a Monte-Carlo simulator for the world cup points prediction. As a Sunday researcher, I am interested in Monte-Carlo simulation and discuss about this method with my colleagues. But, I have not implemented such simulator that simulates specific probability distribution. I see this is a good opportunity to implemented it. My company produces programs that uses a variant of Monte-Carlo simulators. This is good for some specific area, like physical simulation, however, can I use this for world cup prediction? I doubt it. I also don't want to spend more than an hour to implement it. If you are a world cup fun, to simulate it doesn't make sense and no fun, I presume. Also this method can not predict each result anyway. It is like Hari Seldon's Psychohistory in Asimov's Foundation. We could predict average or distribution of the points in this world cup 2010 based...

Page 11: Light implementation In page 11, there is a paragraph about light implementation. Ideally, the performance of the light transport algorithm should depend only on what the scene represents, rather than the details of how it is represented. For example, consider a scene illuminated by a square area light source. If this light source is replaced with a 10 by 10 grid of point sources, then the visual results will be nearly identical. However, the performance of many light transport algorithms will be much worse in the second case. Why 10x10 points is more expensive? As an amateur, I think if the area light is sampled by 20x20, then it seems 10x10 points is cheaper. But this is just an example. It seems the author want to say if you tell the renderer more straight forward way, the rendere can usually optimize the process. It is better to say that an area light is an area light, not an area light is many points. (Thanks to D.S.) Page 14: unbias and consistent This page mentio...

Source code You can find the source code of AB=-BA visualizer here .