Retrieve frequency functions and spectra from the freqfunc format.
Syntax
[w,amp,phas] = getff(g)
[w,amp,phas,sdamp,sdphas] = getff(g,ku,ky)
Description
This function extracts information from the freqfunc format for plotting as an alternative to bodeplot, ffplot, and nyqplot. Results in the freqfunc format are obtained by etfe, spa, and th2ff.
The argument g is the frequency function or spectrum given in the freqfunc format. ku is the chosen input number (only one) and ky is the chosen output number. The noise source is counted as input number 0, so that ku = 0 will extract spectral information.
w is a vector containing the frequency values (in radians/second). amp contains the values of the magnitude (amplitude) of the frequency function and phas contains the phase values (in degrees). The output arguments sdamp and sdphas contain the corresponding standard deviations. All this information is for input number ku and output number ky. If several entries in g correspond to the same input-output pair, then w, amp, phas, sdamp, and sdphas have the corresponding number of columns. The default values of ku and ky are both 1, unless g contains only spectra. In that case getff extracts information about the spectrum corresponding to output number ky.
Examples
Make your own plot of the periodogram with linear scales:
per = etfe(y);
[w,amp] = getff(per);
plot(w,amp)
title('Periodogram of seismic data')
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