harmonograph.r

harmonograph.r

# http://aschinchon.wordpress.com/2014/10/13/beautiful-curves-the-harmonograph/

f1 <- jitter(sample(c(2, 3), 1))
f2 <- jitter(sample(c(2, 3), 1))
f3 <- jitter(sample(c(2, 3), 1))
f4 <- jitter(sample(c(2, 3), 1))
d1 <- runif(1, 0, 1e-02)
d2 <- runif(1, 0, 1e-02)
d3 <- runif(1, 0, 1e-02)
d4 <- runif(1, 0, 1e-02)
p1 <- runif(1, 0, pi)
p2 <- runif(1, 0, pi)
p3 <- runif(1, 0, pi)
p4 <- runif(1, 0, pi)
xt <- function(t) exp(-d1 * t) * sin(t * f1 + p1) + exp(-d2 * t) * sin(t * f2 + p2)
yt <- function(t) exp(-d3 * t) * sin(t * f3 + p3) + exp(-d4 * t) * sin(t * f4 + p4)
t <- seq(1, 100, by=0.001)
dat <- data.frame(t=t, x=xt(t), y=yt(t))
with(dat,
     plot(x,
          y,
          type="l",
          xlim=c(-2, 2),
          ylim=c(-2, 2),
          xlab="",
          ylab="",
          xaxt="n",
          yaxt="n"))