Peter Huybers

Matlab files

  • Multi-taper spectral analysis pmtmPH.m, requires the signal toolbox for Matlab. Note the Matlab pmtm.m routine computes inaccurate error estimates due to problems in the chi2conf subroutine and the assumed number of degrees of freedom. This script uses a fast approximation to compute the 95% confidence limits for a chi-squared distribution and computes the equivalent degrees of freedom [see Percival and Walden, 1993, p256 and p370].
  • Multi-taper coherence analysis cmtm.m, requires the signal toolbox for Matlab and following routines: cohconf.m to calculate confidence levels; cohbias.m to correct for the bias inherent to coherence estimates; and cohbias.mat which is used with cohbias.m. These files allow for the estimation of coherence and phase using the mult-taper method with adaptive weighting. Note that coherence is returned, not coherence-squared, as with the Matlab cohere.m function. Confidence intervals are estimated for both coherence and phase along with an option to plot the results.
  • Here are some demonstration scripts for the above spectral analysis procedures and some other related material. Some supporting files from the below toolbox are also needed.
  • A toolbox of various minor Matlab functions is also available.