Recent Projects in Chasing the tiger

Curlicues

Press the green flag *********************** Ten examples of fractal curlicues . A special program for Scratch .Physicists will recognise a curlicue as a discrete version of Cornu's spiral in optics, and indeed curlicues can be interpreted as diffraction experiments too. ********************** Use the sliders to choose examples and colors and press the green flag. ********************** Reference: F. Berry and J.Golbert,"Renormalisation of Curlicues"in Nonlinearity n°1

Recursion

a teaser, lol!

Tower of Hanoi

This is a tower of hanoi that knows how to solve itself. It is part of the 'Taste of ...' series http://chimu.wordpress.com/a-taste-of-scratch Scratch is an unusual language to program the Tower of Hanoi in because it is missing procedures and recursion. But because of those restrictions, Scratch produces a very interesting and Object-Oriented result. It actually delegates to the Disks better than implementations in other languages like Smalltalk/Squeak or Ruby might choose to do. Comments are in the Stage and the Sprite1 sprite. If you change Sprite1, simply delete the other sprites, duplicate Sprite1, and set the new Sprite2+ disk-ids appropriately. Sprite1 is the prototype for all the other Sprites (kind of like a 'class' but instance-based. See JavaScript, Self, etc. for examples).

Rainbow

-experimental- This project interprets a set of its own musical commands stored in a list to simulate a guitar singer. It's just a quick test of how you can implement your own programming language in Scratch. I'm calling this one Rainbow ;-) Its set of commands is as follows: | - measure mark ||: - start of repeat block :|| - end of repeat block x-chord - play chord n for one measure y - play note y (n-beats) - set duration of following notes rest - rest It works best when downloaded and played in edit mode. Can you transcribe your own songs using this format? Enjoy! -Jens

Sort

This project compares three sommon simple sorting algorithms (bubble, selection, insertion) against two others which I have optimized for Scratch (loops, threads). Select the number of elements to sort and click on the star to start the race. Feel free to remix. Enjoy! -Jens

12xPaint

You've seen this done with the arrow keys...but this one uses the mouse! A paint program that uses 12 brushes at once. CONTROLS: Mouse Button - Pen Up/Down Up/Down Arrows - Pen Size Left/Right Arrows - Background Space - Relocate Center to Mouse Position 1 - Clear Screen 2 - Hide/Show Pens H - Help - Shows the controls NOTES: The biggest problem was making the pen sprites shrink down really small when the pen size was small. Scratch seems to have a lower limit on how small a sprite can be. I ended up having to make a series of special small costumes for the pen sprites for when the pen size was 5 or less.

Three Moths (Sensor Board) v3

This is a sensor board project that I finished up at the Scratch Conference. In general, the program figures out the location of a light sensor (hooked up to resistance-A input) that is held up against the screen. The three moths then fly to that location. The project includes info re how it works. ---- This is presented so that you can see a demo of what it looks like if you don't have a sensor board. Sorry for the quality of the video; I'm just figuring out the shareware I downloaded to make the animated gif. If you just want to use the project and remix it, you can delete the "shell" and "demo" sprites and it will still work.

Cosine Calculation

This project shows how the Cosine function can be calculated using the Taylor Series formula. In this example, I am using only the first 5 terms of the series and getting results accurate to 5 places over most of the range of angles. I've intentionally slowed the calculation down so you can watch the values change as the terms are added on. The values of Cosine are multipled by 100000 so as to work around the limited Scratch variable display which only displays one place to the right of the decimal point. Note that the denominator of the fractions are using Factorial notation with the exclamation mark (!). The factorial of a number is that number times all the integers less than it. For example 8! = 8 * 7 * 6 * 5 * 4 * 3 * 2 * 1 Once you have the Cosine, the Sine can easily be derived using the Pythogorian equation: Sin^2 + Cos^2 = 1 Where ^2 means raised to the second power (squared).

Neural Net 1.1

Forward Propagation Algorithm Neural Networks Basic version 1.1 After learning, can be used for solving other problems......... Neural networks are used for AI and pattern learning (voice/handwriting recognition) for more info about neural networks go to http://neurondotnet.freehostia.com/tutorial/index.html for info about the basis for this code, go to http://fbim.fh-regensburg.de/~saj39122/jfroehl/diplom/e-13-text.html --------------------------------------------------------- Instructions --------------------------------------------------------- So, this may seem really confusing but after reading up on this for only a day, I don't think it's that bad... there are a bunch of variables that you can change- learning rate - lower rate = higher accuracy, more passes in_#1.#2 - the learning rules #1 is which cycle it corresponds to #2 is which neuron it corresponds to target_# - the desired output to teach with # is the cycle it corresponds to other variables are determined by different functions such as errors and out, w#-# are weights that start out random and are what determine the correctness of the function Now for what you can actually do - set 2 input variables for each cycle and set the target you want to get out for that cycle then click learn once it's done learning, you can apply whatever logic it learned to any 2 inputs by changing the values of in_1.1 and in_1.2 then clicking APPLY hope it helps - leave it below!

Logical Array

Watch the Wizard command the individual bits of a variable!

scratchGUIde template

This is a template for an easy Scratch Graphical user interface for applications. I am soon postin tutorials opn hoz to use it, together with an example.

xml

- caution: experimental - this project includes a patch which lets you export scripts (blocks and stacks) into editable text files using an XML format, and import such XML files as scripts back into Scratch. It also tells you how to install this patch into the officially published Scratch source code version. 1.2.1 The XML format produced by this patch is translation independent and should work with any national language you select in Scratch. It also works with any old ('obsolete') blocks of previous Scratch versions, but not with the comment block of the v.1.2 BETA. This patch will not break any compatibility. Any projects created using its features will also work online. Note: This is really only suitable and useful for experienced Squeak hackers. Feel free to use and modify the source code of this patch anyway you like. Have fun! Jens P.S.: you can get the source code following this link: http://scratch.mit.edu/pages/source There's also a helpful forum thread here: http://scratch.mit.edu/forums/viewtopic.php?id=2745

lists

- caution: experimental - this project includes a small patch which lets you experiment with lists (arrays) in Scratch. Note: This is really only suitable and useful for experienced Squeak hackers. Please let me know your thoughts on this. Have fun! Jens P.S.: The code embedded in this project has been superseeded by the one posted at: http://www.chirp.scratchr.org/blog/?p=16

Another Full Raytracer for Scratch 1.2

This is a full raytracer written in Scratch that supports ambient, diffuse, and phong lighting, light occlusion and a single level of reflection. Running this program requires a lot of patience since it can take several hours to render the scene with the pen size set to 2. This was a lot of fun to write. I think the Scratch team has done a wonderful job in developing such an extinsible language.

Snowflake Designer

Snowflake Designer--Click inside the white triangle. Press arrows to change size and shape of cut-out. Just like the paper and scissors version, cut out a pattern in the folded up paper (by clicking) then press space to unfold. This uses some of the v1.2 trig functions as well as a few other things. If you want to cheat and see how it works, press the "C" button while you're creating :)