1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
|
function [g]=ref_iwfac(gf,L,a,M)
%-*- texinfo -*-
%@deftypefn {Function} ref_iwfac
%@verbatim
%REF_IWFAC Compute inverse window factorization
% Usage: g=ref_iwfac(gf,L,a,M);
%
% Input parameters:
% gf : Factored Window
% L : Length of transform.
% a : Length of time shift.
% M : Number of frequency bands.
% Output parameters:
% g : Window function.
%
%@end verbatim
%@strong{Url}: @url{http://ltfat.github.io/doc/reference/ref_iwfac.html}
%@end deftypefn
% Copyright (C) 2005-2016 Peter L. Soendergaard <peter@sonderport.dk>.
% This file is part of LTFAT version 2.2.0
%
% 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/>.
% Calculate the parameters that was not specified
R=prod(size(gf))/L;
N=L/a;
b=L/M;
% The four factorization parameters.
c=gcd(a,M);
p=a/c;
q=M/c;
d=N/q;
gf=reshape(gf,p,q*R,c,d);
% Scale by the sqrt(M) comming from Walnuts representation
gf=gf/sqrt(M);
% fft them
if d>1
gf=ifft(gf,[],4);
end;
g=zeros(L,R);
% Set up the small matrices
for w=0:R-1
for s=0:d-1
for l=0:q-1
for k=0:p-1
g((1:c)+mod(k*M-l*a+s*p*M,L),w+1)=gf(k+1,l+1+q*w,:,s+1);
end;
end;
end;
end;
|
