**R – Fronkonstin**, and kindly contributed to R-bloggers)

For me, mathematics cultivates a perpetual state of wonder about the nature of mind, the limits of thoughts, and our place in this vast cosmos (Clifford A. Pickover – The Math Book: From Pythagoras to the 57th Dimension, 250 Milestones in the History of Mathematics)

I am a big fan of Clifford Pickover and I find inspiration in his books very often. Thanks to him, I discovered the harmonograph and the Parrondo’s paradox, among many other mathematical treasures. Apart of being a great *teacher*, he also invented a family of strange attractors wearing his name. Clifford attractors are defined by these equations:

There are infinite attractors, since a, b, c and d are parameters. Given four values (one for each parameter) and a starting point `(x`

, the previous equation defines the exact location of the point at step _{0}, y_{0})`n`

, which is defined just by its location at `n-1`

; an attractor can be thought as the trajectory described by a particle. This plot shows the evolution of a particle starting at `(x`

with parameters _{0}, y_{0})=(0, 0)`a=-1.24458046630025`

, `b=-1.25191834103316`

, `c=-1.81590817030519`

and `d=-1.90866735205054`

along 10 million of steps:

Changing parameters is really entertaining. Drawings have a *sandy* appearance:

From a technical point of view, the challenge is creating a data frame with all locations, since it must have 10 milion rows and must be *populated* sequentially. A very fast way to do it is using `Rcpp`

package. To render the plot I use ggplot, which works quite well. Here you have the code to play with Clifford Attractors if you want:

library(Rcpp) library(ggplot2) library(dplyr) opt = theme(legend.position = "none", panel.background = element_rect(fill="white"), axis.ticks = element_blank(), panel.grid = element_blank(), axis.title = element_blank(), axis.text = element_blank()) cppFunction('DataFrame createTrajectory(int n, double x0, double y0, double a, double b, double c, double d) { // create the columns NumericVector x(n); NumericVector y(n); x[0]=x0; y[0]=y0; for(int i = 1; i < n; ++i) { x[i] = sin(a*y[i-1])+c*cos(a*x[i-1]); y[i] = sin(b*x[i-1])+d*cos(b*y[i-1]); } // return a new data frame return DataFrame::create(_["x"]= x, _["y"]= y); } ') a=-1.24458046630025 b=-1.25191834103316 c=-1.81590817030519 d=-1.90866735205054 df=createTrajectory(10000000, 0, 0, a, b, c, d) png("Clifford.png", units="px", width=1600, height=1600, res=300) ggplot(df, aes(x, y)) + geom_point(color="black", shape=46, alpha=.01) + opt dev.off()

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