R/ellipse.R

In cwhmisc: Miscellaneous Functions for Math, Plotting, Printing, Statistics, Strings, and Tools

ellipseC <- function(mid, a, b = a, ra = c(-1, 361), phi = 0, k = a*100) {
  k <- abs(mean(k)) # de-vectorize
  ra <- rad(ra)
  alpha <- seq(0, by = (2 * pi) / k, length.out = k + 1)

  c1 <- alpha >= min(ra)
  c2 <- alpha <= max(ra)
  ra <-  (c1 & c2)
  ran <- alpha[ra]
  Z <- complex( real = a * cos(ran), imaginary = b * sin(ran))
  R <- exp(phi * 1i)
  res <- Z * R + mid
  return(res)
}  # end of ellipseC

ellipse1 <- function(a, b = a, ra = c(-1, 361), phi = 0, k = a * 100) {
  ra <- ellipseC(0, a, b = b, ra = ra, phi = phi, k = k)
  res <- cbind(Re(ra), Im(ra))
  return(res)
}  # end of ellipse

conf.ellipse <- function(a, b, phi, df1, df2, level = 0.95, k)
{
  ellipse1(a, b, , phi, k) * qf(level, df1, df2)
}