DefaultSelfSteepening(S_times_dxi,omega,tau,u,U)

%DefaultSelfSteepening An implementation of the self-steepening operator.
%
%    Assuming we are solving the 1D NLSE this applies the default self
%    steepening operator.
%
%     N = DefaultSelfSteepening(S*DXI,OMEGA,TAU,[],[],U,FFTU);
%
%See also: 

% $Author: graceej $ $Date: 2009/10/24 11:08:04 $
% $Revision: 1.3 $


% Copyright (c) 2009, Edward J. Grace
% All rights reserved.
 
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%       disclaimer.
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%       provided with the distribution.
%     * Neither the name of the Imperial College London nor the 
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function N = DefaultSelfSteepening(S_times_dxi,omega,tau,u,U)
    ustar=conj(u);
    ddu = ifft(i.*omega{1}.*U);
    ddustar = ifft(i.*omega{1}.*fft(ustar));
   N = exp(-(2.*ustar.*ddu + u.*ddustar).*S_times_dxi);
end
%% CVS Log
%
% $Log: DefaultSelfSteepening.m,v $
% Revision 1.3  2009/10/24 11:08:04  graceej
% * Modified license to make use of the current BSD style open source initiative license.
%
% Revision 1.2  2009/05/06 20:09:43  graceej
% * Updated make package target to include distribution of the license file and README.
%
% Revision 1.1  2009/04/17 11:42:31  graceej
% * Brought over auto_checking/BPC-LIB tag=end and checked in.
% * This old repository is now defunct.
%
% Revision 1.2  2009/04/17 11:37:25  graceej
% * Wholescale modification of the entire library.
%
% Revision 1.1.2.1  2008/09/16 14:39:59  graceej
% * Added CVS log section.
% * Removed see also link
%
%