Tuesday, December 7, 2010

More fractals!

I don't resist the pleasure to put more pictures I made. In order to achieve the continuous color, I used a trick called "fractal renormalization". In short, after the iteration that put me out of my convergence radius, I chose the color based on the number of iterations minus log(log(|Zn|))/log(2). More information here.






You can find the high resolution of these pictures here:

First image

Second image (detail)

Sunday, December 5, 2010

Fractals!

I recently watched Nova's excellent documentary on fractals. This reminded me of my first programs to render a Julia set, on a 486DX33 running MS-DOS 6.0!

After a few readings in the Internet, I decided to do it again, but this time on my mighty Intel Quad core/2GHz, running Linux Fedora 14.

First hurdle: I never programmed any application whose output is a graphic. So be it, I'll do a small program that will generate a PNG file.

A few attempts later - and discovering that RGB PNG expects you to have 3 bytes per pixel, kind of logical - I did it.

My program is neither smart nor elaborate. But it does the job for Julia sets based on z2+c, where z and c belongs to the set of complex numbers.

The following example is for c=-1.6



And for c=0.256






Going further: if I have a program that can render a Julia set picture for a value of c, I should be able to generate a movie for a path in the set of complex numbers.

Yes. Using the multiple PNGs generated and mencoder (from mplayer), I assembled a couple of animations.


fractal1: from -2 to 2 (works using VLC)

c moves on the line from -2 to 2.

fractal2: sliding a parabola (works using VLC)

c moves along the parabola 2z2-1

Wednesday, December 1, 2010

Fedora 14 - Anjuta crashes or is killed by signal 6 (SIGABRT)

A few days ago, Anjuta started to crash on me. A quick trip to the CLI showed this happened due to not being able to open a library (libsqlite3.so in my case).


Setting the LD_LIBRARY_PATH worked the issue around.


export LD_LIBRARY_PATH=/lib:/usr/lib:/usr/lib64
  Anjuta would now run from the CLI.