function f=comp_igdgt(c,g,a,M,L,c_t,c_f,c_w,timeinv)
%COMP_IGDGT Compute IGDGT
% Usage: f=comp_igdgt(c,g,a,M,L,c_t,c_f,c_w,timeinv);
%
% Input parameters:
% c : Array of coefficients.
% g : Window function.
% a : Length of time shift.
% M : Number of modulations.
% L : length of transform.
% c_t : Centering in time of modulation.
% c_f : Centering in frequency of modulation.
% c_w : Centering in time of window.
% timeinv : Should we compute a time invariant Gabor system.
%
% Output parameters:
% f : Signal.
%
% AUTHOR : Peter L. Søndergaard.
b=L/M;
N=L/a;
Lwindow=size(g,1);
W=size(c,3);
% Pre-process if c_t is different from 0.
if (c_t~=0)
halfmod=repmat(exp(2*pi*i*c_t*((0:M-1)+c_f).'/M),1,N*W);
% The following is necessary because REPMAT does not work for
% 3D arrays.
halfmod=reshape(halfmod,M,N,W);
c=c.*halfmod;
end;
% Eventual phaselocking
if timeinv
c=phaseunlock(c,a);
end;
f=comp_idgt(c,g,a,[0 1],0,0);
% Postprocess to handle c_f different from 0.
if (c_f~=0)
halfmod=exp(2*pi*i*c_f*(0:L-1).'/M);
f=f.*repmat(halfmod,1,W);
end;