Editing R (programming language) (section)

=== Mandelbrot set ===
[[File:Mandelbrot Creation Animation.gif|thumb|200px|"Mandelbrot.gif" graphic created in R. (Note: Colors differ from actual output.)]]
This [[Mandelbrot set]] example highlights the use of [[complex numbers]]. It models the first 20 [[iteration]]s of the [[equation]] <code>z = z<sup>2</sup> + c</code>, where <code>c</code> represents different [[Complex number|complex constants]].

Install the package that provides the <code>write.gif()</code> function beforehand:
<syntaxhighlight lang="r">
install.packages("caTools")
</syntaxhighlight>

R Source code:
<syntaxhighlight lang="r">
library(caTools)

jet.colors <-
    colorRampPalette(
        c("green", "pink", "#007FFF", "cyan", "#7FFF7F",
          "white", "#FF7F00", "red", "#7F0000"))

dx <- 1500 # define width
dy <- 1400 # define height

C  <-
    complex(
            real = rep(seq(-2.2, 1.0, length.out = dx), each = dy),
            imag = rep(seq(-1.2, 1.2, length.out = dy), times = dx)
            )

# reshape as matrix of complex numbers
C <- matrix(C, dy, dx)

# initialize output 3D array
X <- array(0, c(dy, dx, 20))

Z <- 0

# loop with 20 iterations
for (k in 1:20) {

  # the central difference equation
  Z <- Z^2 + C

  # capture the results
  X[, , k] <- exp(-abs(Z))
}

write.gif(
    X,
    "Mandelbrot.gif",
    col = jet.colors,
    delay = 100)
</syntaxhighlight>