Plot Spectra
DESCRIPTION:
Plots the results of a spectrum estimation.
USAGE: 
spec.plot(spec.list, add=F)
REQUIRED ARGUMENTS:
spec.list:
list like that returned by the time series spectrum estimation functions: spectrum, spec.pgram or spec.ar, including at least the components freq and spec.
OPTIONAL ARGUMENTS:
add:
if TRUE, the spectrum plot will be superimposed on an existing spectrum plot. This is useful to compare different spectral estimates for the same series.
SIDE EFFECTS:
plots the spectrum (or spectra for multivariate series) along with a cross in the upper right corner whose vertical component indicate the 95% confidence interval for the spectrum (based on a chi-squared approximation) and whose horizontal element indicates the bandwidth of the estimate. This does not plot the coherency or phase of multivariate series.
SEE ALSO:
spec.ar , spec.pgram , spectrum .
EXAMPLES: 
sun.sp1 <- spec.pgram(sunspots, span=1, plot=T)
sun.sp2 <- spectrum(sunspots, spans=c(19,19,19), plot=F)
spec.plot(sun.sp2, add=T)


spec.plot(sun.sp2)