function retval = U0
  cs = zeros(2,20)
  retval = [];
  for k = 0:1
    for j = 1:20
      cs(k+1,j) = C(k,j);
    endfor
  endfor
  for i = 1:20
    for y = linspace(-1,1,6)
    # retval = [retval ; cs(0,i)*legendreP(0,y) + cs(1,i)*legendreP(1,y)];
    # xz = cs(1,i)*legendreP(0,y) + cs(2,i)*legendreP(1,y)
    retval(end+1) = cs(1,i)*legendreP(0,y) + cs(2,i)*legendreP(1,y);
    endfor
  endfor
endfunction