ift.m

function z = ift(a,dims)
   
% function z = ift(a,[dims]);
% ifft of a with zero frequency in center
% if dims is given, perform ifft on dimension(s) given
% else perform ifft on all dimensions

if nargin==1
    z = fftshift(ifftn(fftshift(a)));
else
    z = a;
    for d=1:length(dims)
        dim = dims(d);
        z = fftshift(ifft(fftshift(z,dim),[],dim),dim);
    end
end