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function cout=comp_irdgt(cin,a,M)

%COMP_IRDGT  Compute inverse real DGT.



N=size(cin,1)/M;

W=size(cin,2);

L=N*a;



cin=reshape(cin,M,N,W);



Mhalf=ceil(M/2);

Mend=Mhalf*2-1;



cout=zeros(M,N,W,assert_classname(cin));



% Copy the first coefficient, it is real

cout(1,:,:)=cin(1,:,:);



cout(2:Mhalf,:,:)=(cin(2:2:Mend,:,:)- i*cin(3:2:Mend,:,:))/sqrt(2);

cout(M-Mhalf+2:M,:,:)= (cin(Mend-1:-2:2,:,:)  +i*cin(Mend:-2:3,:,:))/sqrt(2);



% If f has an even length, we must also copy the Nyquest-wave

% (it is real)

if mod(M,2)==0

  cout(M/2+1,:,:)=cin(M,:,:);

end;