wilbounds.m

来自「Matlab时频分析工具箱,希望能对大家有所帮助啊」· M 代码 · 共 101 行

function [AF,BF]=wilbounds(g,M,L)
%WILBOUNDS  Calculate frame bounds of Wilson basis.
%   Usage:  [AF,BF]=wilbounds(g,M)
%           [AF,BF]=wilbounds(g,M,L)
%
%   Input parameters:
%           g       : Window function.
%           M       : Number of channels.
%           L       : Length of transform to do (optional)
%   Output parameters:
%           A,B   : Frame bounds.
%          
%   WILBOUNDS(g,M) calculates the frame bounds of the
%   Wilson frame operator of the Wilson basis with window g and M
%   channels.
%
%   If the optional parameter L is specified, the window is cut or
%   zero-extended to length L.
%
%   SEE ALSO: GFBOUNDS

% 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(2,3,nargin));

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;


if size(M,1)>1 || size(M,2)>1
  error('M must be a scalar');
end;

if rem(M,1)~=0
  error('M must be an integer.')
end;

if nargin==3
  g=fir2iir(g,L);
else
  L=length(g);
end;

if rem(L,M)~=0
  error('The length of the transform must be dividable by M.');
end;

a=M;

N=L/a;

if rem(N,2)==1
  error('L/M must be even.');
end;


% Get the factorization of the window.
gf=comp_wfac(g,a,2*M);

% Compute all eigenvalues.
lambdas=comp_gfeigs(gf,L,a,2*M);

% Min and max eigenvalue.
AF=lambdas(1);
BF=lambdas(size(lambdas,1));

% Divide by 2 (only difference to gfeigs).
AF=AF/2;
BF=BF/2;

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