R/Bandpass.R

In EarthSystemDiagnostics/paleospec: Spectral tools for the ECUS group

#' @title Calculate  Weights for a Bandpass Filter
#' @description Derive the (smoothed) least square bandpass based on Bloomfield 1976
#' @param omega.upper upper cutoff frequency
#' @param omega.lower lower cutoff frequency
#' @param n length of the filter, has to be odd
#' @param sample sampling rate of the timeseries on which the filter will be applied (1/deltat)
#' @param convergence TRUE: smoothed least square lowpass; FALSE = unsmoothed
#' @return vector of filter weights
#' @author Thomas Laepple
#' @export
Bandpass <- function(omega.upper,
                     omega.lower,
                     n,
                     sample = 1,
                     convergence = T)
{
  if ((n %% 2) == 0)
    stop("N must be odd, this function calculates only symetrical = phase preserving filters")

  return(
    Lowpass(omega.upper, n, sample, convergence) - Lowpass(omega.lower, n, sample, convergence)
  )
}