Michael Jacobsen
Hello from Hugo

Interactive Main and Variance

Michael Jacobsen
This article tries to explain multiple concepts from statistics using a small Javascript illustration of the correlation of two variables. The normal distribution in one dimension is described by the probability distribution $$f(x) = \frac{1}{\sigma \sqrt{2\pi}} e^{-\frac{(x-\mu)^2}{2\sigma^2}}$$ where $$\mu$$ is the mean and $$\sigma$$ is the standard deviation. While the mean is easily understood, the standard deviation measures how spread out the distribution is. A large $$\sigma$$ implies that numbers further from the mean are more likely.

Creating Fractals with Web Workers

Michael Jacobsen
A Web Worker makes it possible to run Javascript code without blocking the user interface. That is, computations can be made in the background without locking the user interface. A Web Worker is created as follows // Main script var worker = new WebWorder( url ); where url must point to a Javascript file. The script is started immediately. This article describes the ‘standard’ Web Worker, not the ‘shared’ Web Worker.

Experiments with PovRay

Michael Jacobsen
All the scenes are version controlled on my GitHub page. You may do whatever with it - but I would like to hear about it - in the unlikely case that anyone do anything like that. Headers In order to improve the look of a previous version of this site, I switched to a theme which included the option to rotate between a number of images in the header. The header1.

Deleting hidden Subversion files before zipping

Michael Jacobsen
Subversion holds various information in .svn directories placed in all directories and sub-directories under version control. Sometimes it is desireable to clean out these files, for example, prior to emailing a zip of the files. I use the awesome tool Total Commander for the job. The procedure is as follows Start Total Commander and make a directory in a scratch area such as c:\temp. Copy the directories to this tempoary directory

Blur - Deblurring an Atmospheric Blurred Image

Michael Jacobsen
During my Ph.D. I made a java applet demonstrating an inverse problem. This article brings the applet back. When light passes throug e.g. air it gets blurred. That is why telescopes are built on top of mountains so that the weak light from the stars travels through less air. The extreme case is the Hubble telescope placed in orbit around the earhth without any atmosphere to distort, i.e., blur the image.

Podcast list

Michael Jacobsen
When washing dishes, mowing the lawn or during commute I enjoy listening to podcasts. The following is a list of my favorite podcasts. I link to their homepage, but you can most likely also find them via iTunes or whatever podcast software you happen to use. First we take the podcasts in English: Hanselminutes is a weekly show with main emphasis on Microsoft technologies, but also other geek related tips.

How far can you see?

Michael Jacobsen
How far can you see when you are, say, 2 meters high? Lets find out assuming that we stand on a perfect circle with perfect visibility (and that we do not have refraction). The Math In Figure 1 I have sketched the situation. The distance (c) is the radius of the sphere (could be the radius of the earth). The distance (a) is the hight of the observer above the circle.

Emacs and DropBox Integration

Michael Jacobsen
If you use more than one computer chances are that you use DropBox to keep a number of often used files syncronized and at hand. I also like to have at least a somewhat similar configuration of various programs on systems. With respect to emacs I have the following .emacs ;; For convenience add the dropbox directory as a variable ;; and set the default directory to that very same one ;; Thus, when storing files you 'start path' will be in ;; the dropbox.

Windows Utilities

Michael Jacobsen
The following is a list of the programs and tools that I install when I get a new computer or reinstall it. I have divided the list into two: The first list contains programs and utilities which can be downloaded and at least tried out for free (some are shareware). The second list contains the proprietary software that I use. Total Commander - a Shareware file manager in the spirit of Norton Commander.