void phone_vec_expand(Phone **ph, int *maxph, int iph);
  /* Assumes that {ph} has been allocated with {maxph} elements. If
    element {ph[iph]} does not exist (i.e. {iph >= maxph}) , reallocates
    {ph} with a large enough size, preserving its old contents. */
   
void phone_vec_trim(Phone **ph, int *maxph, int nph);
  /* Assumes that {ph} has been allocated with {maxph} elements. If 
    {maxph != nph}, reallocates {ph} with size {nph},
    preserving {ph[0..nph-1]}. */

void phone_vec_expand(Phone **ph, int *maxph, int iph)
  { int oldmax = (*maxph);
    Phone *old = *ph;
    if (iph >= oldmax) 
      { int newmax = 2*oldmax;
        if (iph >= newmax) { newmax = iph + 1; }
        newmax += 100;
        Phone *new = (Phone *)malloc(newmax*sizeof(Phone));
        if (old != NULL) 
          { int k; 
            for (k = 0; k < oldmax; k++) { new[k] = old[k]; }
            free(old);
          }
        (*ph) = new;
        (*maxph) = newmax;
      }
  }
      
void phone_vec_trim(Phone **ph, int *maxph, int nph)
  { int oldmax = (*maxph);
    Phone *old = *ph;
    if (nph != oldmax) 
      { Phone *new = (Phone *)malloc(nph*sizeof(Phone));
        if (old != NULL) 
          { int k; 
            for (k = 0; k < nph; k++) { new[k] = old[k]; }
            free(old);
          }
        (*ph) = new;
        (*maxph) = nph;
      }
  }

        
    st_map_init_costs(m, d, e, c);
    int pi;
    for(pi = 0; pi < ph.nel; pi++)
      { Phone *phi = &(ph.el[pi]);
        int vi = phi->vertex;
        VertexData *vd = m->vd[vi];
        Point *vp = &(vd->p);
        /* Find vertices served by {phi}, add a fraction of their demands: */
        double usage = 0.0;
        st_map_compute_costs(m, vi, stopDist, r, &nr, d, e, c);
        int k;
        for (k = 0; k < nr; k++)
          { int wi = r[k];
            ...
            usage += frac*dem[wi];
          }
        phi->usage = usage;
        st_map_reset_costs(m, r, nr, d, e, c);
      }