gfbounds.m

Matlab时频分析工具箱,希望能对大家有所帮助啊

function [AF,BF]=gfbounds(g,a,M,L)
%GFBOUNDS  Calculate frame bounds of Gabor frame.
%   Usage:  fcond=gfbounds(g,a,M);
%           [A,B]=gfbounds(g,a,M);
%           [A,B]=gfbounds(g,a,M,L);
%
%   Input parameters:
%           g     : The window function.
%           a     : Length of time shift.
%           M     : Number of modulations.
%           L     : Length of transform to consider.
%   Output parameters:
%           fcond : Frame condition number (B/A)
%           A,B   : Frame bounds.
%          
%   GFBOUNDS(g,a,M) calculates the ratio B/A of the frame bounds
%   of the Gabor frame with window g, and parameters a, M.
%
%   [A,B]=GFBOUNDS(g,a,M) calculates the frame bounds A and B
%   of the Gabor frame with window g, and parameters a, M. 
%
%   If the optional parameter L is specified, the window is cut or
%   zero-extended to length L.

% 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/>.

error(nargchk(3,4,nargin));

assert_squarelat(a,M,1,'GFBOUNDS',0);

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

Lwindow=length(g);
Ls=Lwindow;

if nargin<4
  [b,N,L]=assert_L(Ls,Lwindow,[],a,M,'GFBOUNDS');
else
  [b,N,L]=assert_L(Ls,Lwindow,L,a,M,'GFBOUNDS');
  g=fir2iir(g,L);
end;

% Handle the Riesz basis (dual lattice) case.
if a>M
  temp=M;
  M=a;
  a=temp;
end;

% Get the factorization of the window.
gf=comp_wfac(g,a,M);

% Compute all eigenvalues.
lambdas=comp_gfeigs(gf,L,a,M);
s=size(lambdas,1);
  
% Min and max eigenvalue.
AF=lambdas(1);
BF=lambdas(s);

if nargout<2
  AF=BF/AF;
end;