# Fractal fundamentals

I am a programmer by trade, and am very interested in fractals.

To be very basic about the concept, one might say a 'circle of circles' is a fractal. Where each circle is made up of circles, and those circles are made of smaller circles and so on.

This idea is similar to a Sierpinski triangle, which I interpret basically a triangle of triangles.

To test my understanding, I decided to draw out this notion of a 'circle of circles'. Realize, I did this by hand with MS paint, copy and paste. I really should have just written out a simple program using some derivative of pi to get a perfect, mathematical display.

In any case, this image is just to illustrate the concept. It's obviously not perfect, my question is: Is the notion of a 'circle of circles', 'triangle of triangles', or 'function of functions' truly the definition of a fractal? And, consequently, is the application of this notion, in this image, a fractal? (I realize it isn't because the alignment is incorrect.)

Note: The coloring was just so I could see the pattern easier, lets assume there is no color. Though if the color had been also repeating, would this still prove true?

I included another, expanding on the use of color: • I quite like the picture you've generated :P – user2662833 Apr 8 '16 at 5:33
• The inside of the entire circle should technically be purple ;) – bigcodeszzer Apr 8 '16 at 6:02
• Or one of the colors actually, depending on which part of the sequence it is zoomed to. – bigcodeszzer Apr 8 '16 at 6:05
• Haha agreed, if you're happy with my answer, could you please consider accepting it as the correct answer :) – user2662833 Apr 8 '16 at 6:40
• Your set is the attractor of an iterated function system, close to one that generates a 9 fold polygasket. Have a look at this poly-gasket visualization. Set the number of sides to 9 and the scaling ratio to 0.25. You will generate an image very close to yours. – Mark McClure Apr 8 '16 at 12:02

A fractal is just a simple rule that you repeat over and over again. You'd be right to say that it is recursive sometimes, but it isn't always generated recursively, indeed many fractals would be impossible to generate with a recursive "seed" so to speak.

# Mandelbrot Set

For example, here is the mandelbrot set: You can generate this picture by making a grid on your computer to represent the complex plane, and assigning a single complex number to each grid cell (for example, the origin would be 0+0i and the right-most point would be 1+0i).

After this, you can just run this simple mathematical function say, 50 times (arbitrary choice):

$$z_{n+1} = z_n^2 + c$$

Where c is a constant of your choosing. If after these 50 iterations, the number you've generated is greater than 2; you've "diverged", so you color that pixel white. Else, you've converged, and you color that pixel white. *you'd want $|c| < 1$ for that reason.

You can generated a colored mandelbrot set by coloring the pixel based on the magnitude after 50 iterations.