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
|
function c=ref_irdftiii(f)
%-*- texinfo -*-
%@deftypefn {Function} ref_irdftiii
%@verbatim
%REF_IRDFTIII Reference Inverse Real DFT type III
% Usage: c=ref_irdftiii(f);
%
% Compute IRDFTIII by explicit formulas.
%
% The transform is orthonormal
%@end verbatim
%@strong{Url}: @url{http://ltfat.github.io/doc/reference/ref_irdftiii.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/>.
L=size(f,1);
Lhalf=floor(L/2);
F=zeros(L);
F(:,1)=ones(L,1);
l=(0:L-1).'/L;
for m=0:Lhalf-1
F(:,2*m+1)=sqrt(2)*cos(2*pi*(m+.5)*l);
F(:,2*m+2)=sqrt(2)*sin(2*pi*(m+.5)*l);
end;
if mod(L,2)==1
F(:,L)=cos(pi*L*l);
end;
F=F/sqrt(L);
% dot-transpose will work because F is real.
c=F*f;
|
