Kategorie: Development

When I was on university we had a PC application for creating geometrical drawings. As I already knew about software development at that time, I was very very impressed by that application.

Was 20 years ago, internet was not yet there at that time, but I did not forget about the program and you can still download it from the company which is developing and selling it.

A couple of years ago, when I had to learn JavaScript, the language for the internet browser, I decided to combine learning with some fun. But it took me much longer than I would have been willing to invest. After a some months, a break of about some years and a restart, here is the result: Lemon City

The difficulty was finding out how to do the geometrical calculations! I never really had vector calculation in school. What I know about it is from some lessons on university. But I was able to find for most of the problems solutions. Some solved in this way, some solved in that way. Once I will come back and read a book about vector calculation and create a new library!

Some features are still missing from the original solution I worked with 20 year ago. But I am already very proud about what I were able to realize. When there is the next time slot where I have enough time, I will continue, for sure.

Here is the result. It took me only minutes to implement it and as you can see in the different sheets, I have also implemented the Julia set in the same workbook.

The sheets are for 3 different resolutions and you see that the range where both sets are visible is from -2.2 / -1.5 to 0.8 / 1.5 for the Mandelbrot set and from -1.8 / -1.5 to 1.8 / 1.5 for the Julia Set.

I realized the different colors with conditional formatting which is a nice feature of Microsoft Excel. Points which are part of the set are black, points which are not part of the set are colored. The color depends on the number of iterations necessary to decide that they are diverting and is going from red and yellow to white.

You can download the Excel workbook from here. You might have to allow the basic script!

I am a fan of the Mandelbrot set since I have seen it the first time. I developed a screen saver for windows which displays the Mandelbrot set and zooms in randomly.

I also tried to develop something similar for the iPhone but did not succeed for the time. When I was investigating possibilities to draw lines in HTML code, I saw that with HTML 5 there is a new tag <Canvas> which allows exactly what I need.

Here is the result. I have created a page which shows the Mandelbrot set and the same for the Julia set. Both are very impressive. You can zoom in by clicking somewhere in the graph and even move the graph with the mouse.

Here is the page with the Mandelbrot set and
here is the page with the Julia Set.

Since I have an iPhone, my wish was to create my own iPhone application. But not so easy as I immediately saw.

First, you have to have a MAC where you can install the iPhone development studio. This was the biggest problem. I buyed an old MAC on ebay but found out, that the MAC I had bought was to old. And after three months it died.

Months later I had the opportunity to buy a Netbook from a friend. And the guy had installed MAC OS on this Netbook. So the biggest hurdle was taken.

The rest was quite simple. For an experienced developer it is not so hard, to learn a new development language within a few days. And after two week or so, I were able to publish my first application.

The application is similar to something I already did years ago for PCs. It is a software which draws a triangle. You can move the corners of the triangle and the most important special points, lines and circles of a triangle are drawn.