**Gnofract 4D** is a free, open source program which allows anyone to create beautiful fractal images.
These include the famous Mandelbrot and Julia sets and many more.
You can explore a universe of images just using a mouse.
It runs on Unix-based systems such as Linux and FreeBSD and can also be run on Mac OS X.
It is easy to use, very fast, flexible, and widely used,with over **125,000** downloads over the past 20 years.

Modern interface (using the GTK toolkit) with unlimited undo, full-screen mode, simple interaction, and quick previews. Explorer Mode and AutoZoom help you find interesting parts of the fractal automatically. Since all formulas are compiled to machine code before being run, you get snappy calculations even on complex custom formulas. Gnofract 4D will take full advantage of multi-core computers for even faster rendering.

Most fractal programs provide a fixed set of formulas. Gnofract 4D’s formula compiler allows you to use any function you can think of. It also supports Fractint and UltraFractal formulas and coloring algorithms so you can use the many thousands of formulas written for those packages. This image is generated from the simple formula below.

```
Jm_25 {
z=#zwpixel,t=p1+4:
z=fn1(z*fn2(z)) + pixel
|z|<=t
}
```

Each base fractal can be displayed in millions of ways, using many coloring algorithms, including old favorites like biomorph, powerful options like Orbit Traps, and unique methods like Hot and Cold. Display multiple fixed points, critical values, or other regions using the “fate” option. This image shows the two basins of attraction of the Cubic Mandelbrot.

What sets it apart from other fractal programs (and makes it “4D”) is the way that it treats the Mandelbrot and Julia sets as different views of the same four-dimensional fractal object. This allows you to create images which are a cross between the two sets and explore their inter-relationships.