%CEMDC2_FIX  bivariate Empirical Mode Decomposition, second algorithm
%
%
%   Syntax
%
%
% [IMF,NB_ITERATIONS]=CEMDC2_FIX(T,X,NB_ITERATIONS,MAX_IMFS,NDIRS);
%
%
%   Description
%
%
% computes bivariate EMD, second algorithm [1] with NB_ITERATONS sifting
% iterations for each IMF
%
%   mean of boolean array {(mean_amplitude)/(envelope_amplitude) > THRESHOLD} < TOLERANCE
%
% inputs:	
%       - T: sampling times. If T=[], the signal is assumed uniformly sampled.
%       - X: analyzed signal
%       - NB_ITERATIONS: number of sifting iterations to be performed to
%         extract each IMF. If NB_ITERATIONS is empty or unspecified, 10 iterations 
%         are performed by default.
%         Note: The effective number of sifting iterations might be less 
%         than NB_ITERATIONS for the last modes if the sifting process has 
%         to be stopped because of a lack of extrema.
%       - MAX_IMFS: maximum number of IMFs to be extracted. If MAX_IMFS is
%         zero, empty or unspecified, the default behavior is to extract as
%         many IMFs as possible.
%       - NDIRS: number of directions used to compute the local mean.
%         If unspecified, the default value is 4.
%         rem: the actual number of directions (according to [1]) is 2*NDIRS
%         
% outputs: 
%		- IMF: intrinsic mode functions (IMFs) (last line = residual)
%		- NB_ITERATIONS: effective number of sifting iterations for each mode
%
%
%   Examples
%
%
% workspace: 
%  T: 1xN time instants
%  X: 1xN signal data 
%
%>>IMF = CEMDC2_FIX(T,X);
%>>[IMF,NB_IT] = CEMDC2_FIX([],X);
%>>IMF = CEMDC2_FIX(T,X,20);
%>>[IMF,NB_IT] = CEMDC2_FIX([],X,[],4);
%
%
%   References
%
%
% [1] G. Rilling, P. Flandrin, P. Gon鏰lves and J. M. Lilly.,
% "Bivariate Empirical Mode Decomposition",
% Signal Processing Letters (submitted)
%
%
% See also
%  (c)emd_visu (visualization),
%  emd (slow but has many options),
%  cemdc2, cemdc, cemdc_fix (other fast implementations of bivariate EMD)
%
%
% G. Rilling, last modification: 3.2007
% gabriel.rilling@ens-lyon.fr
%
% code based on a student project by T. Boustane and G. Quellec, 11.03.2004
% supervised by P. Chainais (ISIMA - LIMOS - Universite Blaise Pascal - Clermont II
% email : pchainai@isima.fr).