R/COI.R

In WaveletComp: Computational Wavelet Analysis

COI <-
function(start = start, dt = dt, nc = nc, nr = nr, Period = Period){

  axis.1 = seq(from = start, by = dt, length.out = nc)
  axis.2 = log2(Period)
  
  # Define central angular frequency omega0 and fourier factor:
  omega0 = 6.0  
#   fourier.factor = (4*pi)/(omega0 + sqrt(2+omega0^2))
  fourier.factor = (2*pi)/omega0
  
  coi = fourier.factor * sqrt(2) * dt * c(1E-5, 1:((nc+1)/2-1), rev((1:(nc/2-1))), 1E-5)
  coi.x = c(axis.1[c(1, 1)] - dt*0.5, axis.1, axis.1[c(nc, nc)] + dt*0.5)
  logyint = axis.2[2] - axis.2[1]
  yl = c(log2(Period[nr]) + 0.5*logyint, log2(Period[1]) - 0.5*logyint)
  yr = rev(yl)
  coi.y = c(yl, log2(coi), yr)
	
  # Output
  output <- list(x = coi.x, y = coi.y, axis.1 = axis.1, axis.2 = axis.2)
  return(invisible(output))
}

## Major part of this code: Tian, H. and Cazelles, B., \code{WaveletCo}