   real dpdx = 0.5 * (pe - pw) * ddx;
   real dpdy = 0.5 * (pn - ps) * ddy;
   real dpdz = 0.5 * (pt - pb) * ddz;
+*/
 
   pp[node+nnodes*part] = pc + dpdx*(x-xx) + dpdy*(y-yy) + dpdz*(z-zz);
   // switch to particle rest frame

  real dpdx = 0.5 * (pe - pw) * ddx;
  real dpdy = 0.5 * (pn - ps) * ddy;
  real dpdz = 0.5 * (pt - pb) * ddz;
*/

  real a = dt0/dt;
  a = (a + 2.)/(a + 1.);
  real pc = p[C]*a + p0[C]*(1.-a);

  real dpdz = 0.5 * (pt - pb) * ddz;
*/

  real pc = p[C];
  real pw = p[C-1];
  real pe = p[C+1];
