function[f]=transfreq(i1,i2)% TRANSFREQ  Wavelet transform freqeuncy.%  %   F=TRANSFREQ(W) where W is a wavelet transform array computes the%   *cyclic* wavelet transform frequency F using the first central %   difference and assuming a unit sample rate.  F has the same size %   as W.%%   F=TRANSFREQ(DT,W) instead uses timestep DT to compute the %   transform frequency F. %%   In order that F the generally positive, in keeping with the %   convention of Lilly and Gascard (2006), the sign of F is chosen %   such that its mean value is positive.%%   See also WAVETRANS, RIDGEWALK.%%   Usage: f=transfreq(w);%          f=transfreq(dt,w);%   _________________________________________________________________%   This is part of JLAB --- type 'help jlab' for more information%   (C) 2006 J.M. Lilly --- type 'help jlab_license' for details        if nargin==1    dt=1;    w=i1;else    dt=i1;    w=i2;end%/***********************************************************%Frequencyf=frac(1,2*pi*dt)*vdiff(unwrangle(imlog(w)),1);for k=1:size(w,3)    if vmean(vmean(f(:,:,k),1),2)<0,       f(:,:,k)=-f(:,:,k);    endend%\********************************************************