Aart's Blog

Since the moon is back at a normal hour, I could do some more experiments with astrophotography. Below a comparison between prime focus and 9.7mm eyepiece projection photograph of the moon using an Meade ETX-90EC. Disappointing result for the latter, since a digital zoom on the prime focus photo is much more clear.

If you are following me on Facebook or Google+, you probably noticed that lately I have been less busy with chess programming . Instead I have been spending  free time at my Meade ETX-90EC telescope getting familiar with astrophotography . Here are some of my first pictures using prime focus configuration (single shot manual exposure, using mirror lockup and remote control to minimize vibrations).  I really like the clarity of the moon picture and was happy seeing the ring of Saturn so clearly. I also tried eyepiece projection configuration , but found this extremely challenging. Due to the inherent light loss at higher magnifications, it is very hard to find and focus the object (hints from experienced astrophotographers welcome!). Today I have been experimenting with the different configurations during daytime. Below you see some sample pictures of my neighbors house number sign, taken with the camera's 300mm telelens for reference and three ETX configuratio...

More engines were added to the Chessbase compatible engines for Android package . Many thanks to the engine authors for their explicit permission.

I am about to release a next version of Chess for Android that recognizes engines in the Chessbase compatible format discussed in the previous blog posting. The new version is available as direct download or from Google Play . With this release, all engines installed in this format (either the engines that ship with the Chessbase for Android application itself, or engines installed in this format, such as my own Engines.apk package) are available for direct import in Chess for Android as well as in the latest Chessbase for Android . Together with sharing capabilities, this greatly enhances the 'chess ecosystem' on Android, since chess GUIs can now be used interchangeably in a much simpler manner. As before, engines authors that want to be included in the package can drop me an email.

Chessbase announced UCI engine support in Chessbase for Android too. Great news! I have packaged some chess engines in Chessbase compatible format so that they are directly available in that application. I will also release a new version of Chess for Android that supports this format to keep the chess ecosystem complete. Simply download and install my Chess Engines Package, available at  Google Play . For now, the package only contains a few engines, but any chess author that wants to be included is welcome to drop me an email with permission to include the binary in the application.

Today, the last five seconds-per-move tournament in Group A completed, played from both sides of all positions in the Silversuite gambit opening suite. The Komodo DEV engine crashed in a few fixed positions, and the games had to be adjudicated, unfortunately. Games available at the tournament site . This concludes my 2013 Android engines tournament. Congratulations to Richard Vida for Critter's victory, his second Android tournament victory!                                 1 Critter 1.6a     *         27.5-22.5 38.0-12.0 38.0-12.0 48.0- 2.0 151.5/200 2 Stockfish 2.3.1  22.5-27.5 *         42.0-8.0  37.5-12.5 45.5- 4.5 147.5/200 3 Toga II 3.0      12.0-38.0  8.0-42.0 *    ...

Group B in the ongoing 2013 chess tournament between UCI and XBoard engines for Android just completed a five seconds-per-move tournament played from both sides of all positions in the Silversuite gambit opening suite. Congratulations, again, to Toga II, which was updated from version 1.4.1SE to version 3.0, for its promotion to Group A. Games available at the tournament site .                    1         2         3         4         5 1 Toga II 3.0      *         26.5-23.5 33.5-16.5 46.0- 4.0 45.5- 4.5 151.5/200 => TO A 2 Gaviota v0.86    23.5-26.5 *         33.0-17.0 36.5-13.5 44.0- 6.0 137.0/200 3 DiscoCheck 4.0....

Here is one of the first examples I tried, taken from the 1981 high school sample exams. Consider the function f given by x -> x^2 / (x |x| + 1). On the TI-89, it is best to enter functions in the Y= window for easy reference later. The calculator also features pretty printing of the function after entering the raw definition, as shown below using the y1 slot. Now, the graph feature plots the function, nicely accounting for the asymptotes. One of the questions was to solve f(x) < 1/2 x. On the TI-89, this can be done with the solve function on the just entered y1 function. The solution is given on one line, so a bit of scrolling is required, but it is correct. Another question was to compute the area under the function on the interval [0,1]. This is easily done with the integral function, as shown below. Pretty neat, right?

I treated myself with this Texas Instruments TI-89 Titanium calculator . I really like the computer algebra system and graphic capabilities. Although a bit retro compared with what one can do on a regular desktop, I was impressed to see this calculator solve all my high school advanced calculus questions symbolically by just pressing a few buttons.

Group C in the ongoing 2013 chess tournament between UCI and XBoard engines for Android just completed a five seconds-per-move tournament played from both sides of all positions in the Silversuite gambit opening suite. Congratulations to Toga II for its promotion to Group B. Games available at the tournament site .                                                  1 Toga II 1.4.1SE *         30.0-20.0 33.5-16.5 36.0-14.0 37.5-12.5 137.0/200 => B 2 Arasan 15.2 JA  20.0-30.0 *         27.0-23.0 27.5-22.5 35.0-15.0 109.5/200 3 Texel 1.01      16.5-33.5 23.0-27.0 *         29.5-20.5 35.0-15.0 104.0/200 4...