Hi all,

Here, specificly I want to introduce one of my programs which visually represents the Relativity theory...

You enter the initial length, mass and time of the object and the speed...it calculates the length, mass and time in that speed with a downloadable visual representation.

you can try it here:
http://www.dreamstube.com/php/relativity/

enjoy and please let me know about your feedback.

If you are a flash/php programmer, you might be interested in this link:

http://us2.php.net/manual/en/book.swf.php

If you've worked with graphic softwares like Freehand, you should be familar with the Bezier Curve. 

According to WiKipedia, In the mathematical field of numerical analysis, a Bézier curve is a parametric curve important in computer graphics and related fields. Generalizations of Bézier curves to higher dimensions are called Bézier surfaces, of which the Bézier triangle is a special case.

I used GD graphic library and eval() fucntion is PHP to develop the Bezier class. This class takes the coordinates of 4 points needed for a bezier curve and draws it in an image. This image can be saved like any other web image. You can draw your own Curve by clicking on the following sample image.

The class code can be downloaded from my page in phpclasses.org.

I developed this class long time ago just for fun. It outputs the calendar of a given month and year including future dates as an HTML table.

The width of the calendar table is also configurable.
Leap years are handled correctly. Try it by clicking on the sample images.

Try it here! 

According to Wikipedia, A fractal is generally "a rough or fragmented geometric shape that can be split into parts, each of which is (at least approximately) a reduced-size copy of the whole,"^[1] a property called self-similarity.  

Recently I added a post about a Silverlight application to draw Koch Curves. I re-programmed it in PHP using the PHP GD image library. The output is a Jpeg and can be saved like a normal image. You can try the application by clicking on the sample image. The only input you need to provide is the number of iterations (levels) which can be selected from the given dropdown.

You can also download the PHP code from phpclasses.org. Click on the sample image to try it yourself.

The applications that let the users compose text, for instance, of articles or e-mail messages, can benefit of text spelling features as they let the users review and eventually fix spelling mistakes before submitting the final version of the texts that are composed.

PHP comes with text spelling extensions like pspell but in some installations these extensions are not available.

This class provides a text spelling solution completely based on PHP code that only uses basic functions

The class makes it possible to provide text spelling features without depending on the availability of PHP spelling extensions.

You can try it here. The code is also downloadable here. I won the December 2004 phpclasses.org prize for this application.

Here I'm introducing an interesting PHP program.

You can pass an expression, f(x) and a range for your x variable and it draws the functions diagram for you. The generated diagram can be saved an a normal image.

Here you can see a sample diagram for f(x) = sin(x/10)

Try it yourself here. The code also can be downloaded from phpcclasses.org .

When I was a student at universoty, I used to do lots of scientific PHP programs just for fun. Here is the one I really like. After 7 years I still can spend time playing with it and graw really cool graphs.

This PHP application takes 3 parametric expressions for x, y and z dimentions and draws the 3D graph representing the expressions. You can also save the result as an ordinary image. This program is really useful for students who like mathematics and algebra. 

t, is the variable which changes within the range you provide so foreach specific t, we will get a x, y and z values which will form our cool 3D graph

Here is a sample output:

You can try it here. Just make sure you type the expressions in C++ (PHP) format. This code can be downloaded here.