kolmog.m

著名的seismiclab的代码 是地震学研究人员必备的工具

function [w_min] = kolmog(w);  
%KOLMOG: Kolmogoroff spectral factorization
%        Given an arbitrary wavelet this
%        function retrieves the minimum phase
%        wavelet using the Hilbert transform
%
%  [w_min] = kolmog(w)
%
%  IN   w:     a wavelet of arbitrary phase (1 column or 1 row)
%
%  OUT  w_min: a min phase wavelet 
%
%
%  Example:
%            w = [1,2];   
%            w_min = kolmog(w);  
% 
%  SeismicLab
%  Version 1
%
%  written by M.D.Sacchi, last modified December 10,  1998.
%  [e-mail] 
% 
%  Copyright (C) 1998 Seismic Processing and Imaging Group 
%                     Department of Physics
%                     The University of Alberta 
%
%


nw = max(size(w));    % lenght of the wavelet
nfft = 4*( 2^nextpow2(nw));

W = log ( abs(fft(w,nfft))+1.e-25 );
W = ifft(W);

for i=nfft/2+2:nfft; W(i)=0.;end;
W = 2.*W;
W(1) =W(1)/2.;

W = exp(fft(W)) ;
w_min = real(ifft(W));
w_min = w_min(1:nw); 

return