function expand_2d,a
  s=(size(a,/dimensions))
  b=dblarr(s*2-1)*!values.d_nan
  for i=0,s[0]-1 do begin
    for j=0,s[1]-1 do begin
;      for k=0,s[2]-1 do begin
;        for l=0,s[3]-1 do begin
          b[i*2,j*2]=a[i,j]
;        end
;      end
    end
  end
  return,b
end