Lorenz Attractor by Zio Chris

The Lorenz Attractor^? is another classic fractal, discovered by Edward Lorenz, as he was trying to model the weather. He also coined the term "the butterfly effect", to capture the idea that small changes in one place and time can have unpredictable consequences elsewhere later. The term comes from the idea of a butterfly flapping its wings setting off a chain of events that leads to a hurricane weeks later in another part of the world. Is it a coincidence that the first version of the attractor that Lorenz created sort of looks like a butterfly? Hmm...
Like the De Jong attractor, and different from the Mandelbrot set and the Burning Ship fractal, here we have three parameters that we can adjust to get different images. Unlike the other fractals here, the Lorenz attractor is 3 dimensional. However, we are only plotting two dimensions at a time. We use the third dimension as the source of information about the color. As with the De Jong attractor, there is no standard use of colors.
The examples here include the standard "butterfly" one, as well as some more unusual ones, not typically seen on the web. As with the other fractal examples here, this pages owes a lot to Paul Bourke, specifically his Lorenz Attractor page and the Wikipediage Lorenz Attractor page.

The Lorenz attractor, like the De Jong attractor is visualized as a series of points, calculated by equations with parameters, and starting from a particular point. The equations are:
 
nextX = previousX + dt * r * (previousY - previousX);
nextY = previousY + dt * (previousX * (b - previousZ) - previousY);
nextZ = previousZ + dt * (previousX * previousY - p * previousZ);
 
dt is a small factor that incorporates the notion of change of time. The Wikipediage Lorenz Attractor page has some useful technical details about the parameters and their range of values, including the idea that the parameters are typically positive.