dplR (version 1.4.9)

ffcsaps: Smoothing Spline with User-Specified Rigidity and Frequency Cutoff

Description

Applies a smoothing spline to y with rigidity determined by two parameters: frequency response f at a wavelength of nyrs years.

Usage

ffcsaps(y, x=seq_along(y), nyrs=length(y)/2, f=0.5)

Arguments

y

a vector, typically a tree-ring series.

x

a vector with length(y), typically giving the years of y.

nyrs

a number greater than 1, affecting the rigidity of the spline. When f is kept constant, a larger nyrs produces a more rigid spline. Defaults to length(y)/2.

f

a number between 0 and 1 giving the frequency response at a wavelength of nyrs years. When nyrs is kept constant, a smaller f produces a more rigid spline: At one extreme, f=0 causes the

Value

• A filtered vector.

Details

This applies a smoothing spline similar to the spline applied in most dendrochonological software. See references for more information.

References

Cook, E.R. and Kairiukstis, L.A. (1990) Methods of Dendrochronology: Applications in the Environmental Sciences. Springer. ISBN-13: 978-0792305866.

See Also

hanning detrend

Examples

# Use series CAM011 from the Campito dataset
  data(ca533)
  series = ca533[,"CAM011"]
  series=series[!is.na(series)]
  plot(series,type='l',ylab='Ring Width (mm)',col='grey')
  lines(ffcsaps(series,nyrs=32),col='red',lwd=2)
  lines(ffcsaps(series,nyrs=64),col='green',lwd=2)
  lines(ffcsaps(series,nyrs=128),col='blue',lwd=2)

  # Use first series from the Mesa Verde dataset
  data(co021)
  series = co021[,1]
  series=series[!is.na(series)]
  plot(series,type='l',ylab='Ring Width (mm)',col='grey')
  lines(ffcsaps(series,nyrs=32),col='red',lwd=2)
  lines(ffcsaps(series,nyrs=64),col='green',lwd=2)
  #nyrs defaults to 0.5*length(series) = 347
  lines(ffcsaps(series),col='blue',lwd=2)