% Call: ft_pst.m 
% Calculation of the splitting-signal, or image-signal 
% which is generated by the frequency (p,s) in the 
% tensor representation of the image A of size NxM 
% where N=M>1 is an arbitrary integer. 
%
% Dr. Artyom Grigoryan, 1996 (modified 2009)

function B=ft_pst(A,p,s)
   [M N]=size(A);
   B=zeros(1,N);
   ks=0;
   for m=1:M
      t=ks;
      for n=1:N  
         if t>=N t=t-N; end; 
         t1=t+1;
         B(t1)=B(t1)+A(m,n);
         t=t+p; 
      end;
      ks=ks+s;
      if ks>=M ks=ks-M; end;
   end;
%  B=B/N;