% Two and threedimensional (centered) Fourier transformation
% where the input can be subject to rigid body motion:
%    derivative
%
% (c) by Hannes Nickisch & Alexander Loktyushin, 
%                               MPI for Biological Cybernetics, 2011 February 02

function dAi = d(A,i)
  A.dkind = i;               % which derivative, 0 means all of the respective kind
  dAi = A;                                                  % assign output
  
  