wildual.m

Matlab时频分析工具箱,希望能对大家有所帮助啊

function [gamma]=wildual(g,M,L)
%WILDUAL  Canonical dual window.
%   Usage:  gamma=wildual(g,M);
%           gamma=wildual(g,M,L);
%
%   Input parameters:
%         g     : Gabor window.
%         M     : Number of modulations.
%         L     : Length of window. (optional)
%   Output parameters:
%         gamma : Canonical dual window.
%
%   WILDUAL(g,M) returns the dual window of the Wilson or MDCT basis with
%   window g, parameter M and length equal to the length of the window g.
%
%   WILDUAL(g,M,L) does the same, but now L is used as the length of the
%   Wilson basis. g will be cut or zero-extended to length L.
%
%   The input window g must be whole-point even. If g is not whole-point
%   even, then reconstruction using the dual window will not be perfect.
%
%   SEE ALSO:  WILORTH, ISEVEN

% This program is free software: you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation, either version 3 of the License, or
% (at your option) any later version.
% 
% This program is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
% GNU General Public License for more details.
% 
% You should have received a copy of the GNU General Public License
% along with this program.  If not, see <http://www.gnu.org/licenses/>.

%   Author : Peter Soendergaard.

error(nargchk(2,3,nargin));
  
wasrow=0;

if size(g,2)>1
  if size(g,1)>1
    error('g must be a vector');
  else
    % g was a row vector.
    wasrow=1;
    g=g(:);
  end;
end;
  
assert_squarelat(M,M,1,'WILDUAL',0);

Lwindow=length(g);
Ls=Lwindow;

% There is no reason to do special support for FIR Wilson windows

if nargin<3
  [b,N,L]=assert_L(Ls,Lwindow,[],M,2*M,'WILDUAL');
else
  [b,N,L]=assert_L(L,Lwindow,L,M,2*M,'WILDUAL');
  g=fir2iir(g,L);
end;

  
% If input is real, output must be real as well.
inputwasreal = isreal(g);

a=M;
  
gf=comp_wfac(g,a,2*M);
gammaf=2*comp_candual_fac(gf,L,a,2*M);
gamma=comp_iwfac(gammaf,L,a,2*M);

if inputwasreal
  gamma=real(gamma);
end;
      
if wasrow
  gamma=gamma.';
end;