Data commit

Task/Mandelbrot-set/R/mandelbrot-set-1.r

@@ -0,0 +1,23 @@
+iterate.until.escape <- function(z, c, trans, cond, max=50, response=dwell) {
+  #we iterate all active points in the same array operation,
+  #and keeping track of which points are still iterating.
+  active <- seq_along(z)
+  dwell <- z
+  dwell[] <- 0
+  for (i in 1:max) {
+    z[active] <- trans(z[active], c[active]);
+    survived <- cond(z[active])
+    dwell[active[!survived]] <- i
+    active <- active[survived]
+    if (length(active) == 0) break
+  }
+  eval(substitute(response))
+}
+
+re = seq(-2, 1, len=500)
+im = seq(-1.5, 1.5, len=500)
+c <- outer(re, im, function(x,y) complex(real=x, imaginary=y))
+x <- iterate.until.escape(array(0, dim(c)), c,
+                          function(z,c)z^2+c, function(z)abs(z) <= 2,
+                          max=100)
+image(x)

Task/Mandelbrot-set/R/mandelbrot-set-2.r

@@ -0,0 +1,16 @@
+#install.packages("caTools") # install external package (if missing)
+library(caTools)             # external package providing write.gif function
+jet.colors <- colorRampPalette(c("red", "blue", "#007FFF", "cyan", "#7FFF7F",
+                                 "yellow", "#FF7F00", "red", "#7F0000"))
+dx <- 800                    # define width
+dy <- 600                    # define height
+C  <- complex(real = rep(seq(-2.5, 1.5, length.out = dx), each = dy),
+              imag = rep(seq(-1.5, 1.5, length.out = dy), dx))
+C <- matrix(C, dy, dx)       # reshape as square matrix of complex numbers
+Z <- 0                       # initialize Z to zero
+X <- array(0, c(dy, dx, 20)) # initialize output 3D array
+for (k in 1:20) {            # loop with 20 iterations
+  Z <- Z^2 + C               # the central difference equation
+  X[, , k] <- exp(-abs(Z))   # capture results
+}
+write.gif(X, "Mandelbrot.gif", col = jet.colors, delay = 100)