   real dpdz = 0.5 * (pt - pb) * ddz;
 */
 
-/*
   real pc = p[C];
   real pw = p[C-1];
   real pe = p[C+1];

  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 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
