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TI-89 calculator example

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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?

TI-89 graphic calculator

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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.

Android Tournament: Group C

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 crafty-235      14.0-36.0 22.5-27.5 20.5-29.5 *         30.0-20.0  87.0/200
5 Rotor 0.8       12.5-37.5 15.0-35.0 15.0-35.0 20.0-30.0 *          62.5/200

Android Tournament: Group D

Group D 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 Crafty its promotion to Group C.

Games available at the tournament site.

1 crafty-235      *         31.0-19.0 34.5-15.5 31.5-18.5 37.5-12.5 134.5/200 => C
2 cheng3 1.07 JA  19.0-31.0 *         25.0-25.0 30.5-19.5 33.0-17.0 107.5/200
3 Daydreamer 1.75 15.5-34.5 25.0-25.0 *         26.5-23.5 30.0-20.0  97.0/200
4 scorpio-27-ja   18.5-31.5 19.5-30.5 23.5-26.5 *         29.0-21.0  90.5/200
5 GarboChess 3    12.5-37.5 17.0-33.0 20.0-30.0 21.0-29.0 *          70.5/200

Android Tournament: Group E

Group E in my 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 Garbochess 3 for its promotion to Group D.

Games available at the tournament site.

1 GarboChess     *         26.5-23.5 32.5-17.5 32.5-17.5 33.5-16.5 125.0/200 => D
2 sloppy-023-ja  23.5-26.5 *         25.0-25.0 31.0-19.0 23.0-27.0 102.5/200
3 danasah-488-ja 17.5-32.5 25.0-25.0 *         23.0-27.0 29.5-20.5  95.0/200
4 tucano104-ab   17.5-32.5 19.0-31.0 27.0-23.0 *         25.5-24.5  89.0/200
5 betsabe-II-130 16.5-33.5 27.0-23.0 20.5-29.5 24.5-25.5 *          88.5/200

Android Tournament: Group F

The test and qualification rounds of my 2013 chess tournament between UCI and XBoard engines for Android are over and the group tournaments have started.

Group F just completed a five seconds-per-move tournament in Group F played from both sides of all positions in the Silversuite gambit opening suite. Congratulations to betsabe-II-130-android-ja for its promotion to Group E.
Games available at the tournament site.
1 betsabe-II-130     *         26.0-24.0 31.0-19.0 36.0-14.0 37.5-12.5 130.5/200 => E
2 phalanx-xxii-ja    24.0-26.0 *         21.5-28.5 33.5-16.5 37.0-13.0 116.0/200
3 typhoon-android-ja 19.0-31.0 28.5-21.5 *         28.0-22.0 35.0-15.0 110.5/200
4 TJchess 1.01U      14.0-36.0 16.5-33.5 22.0-28.0 *         27.0-23.0  79.5/200
5 kmtchess-121-ja    12.5-37.5 13.0-37.0 15.0-35.0 23.0-27.0 *          63.5/200

Test Runs for the 2013 Tournament

I have completed the initial tests for the 2013 tournament between engines for Android (compiled for ARMv5TE) using Chess for Android on a Nexus 7 (1.3 GHz quad-core Cortex-A9). The qualified and disqualified engines are shown below.  Next to follow is a qualification tournament which will place the top 25 engines in six groups, like I did in the 2011 tournament.
However, I will wait a few days to see whether engine authors want to appeal the disqualification with an improved binary. Updates of qualified engines are of course also welcome.
Qualified:

AdroitChess 0.3     
Arasan 14.0.1
betsabe-II-130-android-ja
BikJump v2.1P (32-bit)
cheng3 1.07 JA
crafty-235-android-ja
Critter 1.6a 32-bit
danasah-488-ja
Daydreamer 1.75 JA
Diablo 0.5.1      
DiscoCheck 4.0.1  
exchess-054-beta-ja
fairymax48l-ab   
GarboChess 3 (32-bit)
Gaviota v0.86    
gk-090-ja   
GNU Chess 6.0.2
greko98-ab   
Jazz 6.40 JA
kmtchess-121-ja 
myrddin0.85j     
natwarlal-014-ja     
olithink-531-ja
Pepito v1.59  
phalanx-xxii-ja…

2013 Android Engine Tournament

My 2013 tournament between UCI and XBoard engines for Android (ARMv5TE-based) using Chess for Android is about to start with the test and qualifying rounds. I have setup a tournament website with past tournaments (one old, one new so far). The new tournament results will be posted in this blog and at the 2013 tournament site. Games will be played on a Nexus 7 (1.3 GHz quad-core Cortex-A9). If supported, engines will be allowed to use multi-threading.

Let the games begin! If you don't see your favourite engine in the test tournaments, feel free to drop me a request.

Chess for Androidv 4.1.5

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I just released version 4.1.5 of Chess for Android as direct download and at Google Play with enhancements for, what I like to call, the chess ecosystem on Android. First, as explained in my prior blog posting, Chess for Android now understands a few more direct sharing requests from other applications so that, for example, a game can be shared directly from Gerhard Kalab's Chess PGN viewer into Chess for Android, without going through tedious copy-and-paste operations. Conversely, Chess for Android now supports the "Share Game" feature as well to do the opposite operation.
As illustrated below (long-press notation window to open the extended menu), exporting a game from Chess for Android to the Chess PGN Viewer now only takes a few simple clicks!


More on application/x-chess-pgn

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In January 2012, I posted a blog entry on registering Chess for Android as viewer for the application/x-chess-pgn MIME type. Under this approach, when an Android application requests viewing a game in PGN format, Chess for Android will open that game. If several programs register as viewer, the user can select what program should be used.

Recently, I got an email from Gerhard Kalab, author of Scid on the Go and Chess PGN Viewer, with a request to support the application/x-chess-pgn MIME type for data sent through an Intent.EXTRA_TEXT as well. After adding this feature, Gerhard's viewer can now share a game with Chess for Android, as shown below. For example, to share a game from the Chess PGN Viewer, press menu, select "Share", and then "Share game". This lists possible target programs, including Chess for Android. Picking the latter opens Chess for Android with the currently viewed game.

Nice to see the Android chess ecosystem develop more and more!