/* superposition */
/* requires each dose on file */
/* loop until all rows processed (nn) */
/* if first.subject, must have loading dose - Dose[0] */
/* if dose record, count dose and time (mm) , put into array */
/* if conc record, loop j=0 to mm, input dose and time from array */

void 
nlme_one_comp_first (longint *nrow, double *Resp, double *inmat)
{
  longint i, j, nn = *nrow, mm = 0;
  double v, cl, *tl = Calloc(nn, double), *ds = Calloc(nn, double),
    *Subject, *Time, *Dose, *V, *Cl,
         sl = DOUBLE_EPS;	/* sl is last subject number, usually */
				/* an integer but passed as double. */
				/* It is started at an unlikely value. */
  Subject = inmat;
  Time = inmat + nn;
  Dose = inmat + 2 * nn;
  V = inmat + 3 * nn;
  Cl = inmat + 4 * nn;
  for(i = nn; i--; Resp++, Subject++, Time++, Dose++, V++, Cl++) {
    v = *V; cl = *Cl;
    *Resp = 0;
    if (*Subject != sl) {	/* new Subject */
      if (is_na_DOUBLE(Dose)) {
	PROBLEM
	  "First observation on an individual must have a dose"
	  RECOVER(NULL_ENTRY);
      }
      sl = *Subject;
      mm = 0;
      tl[mm] = *Time;
      ds[mm] = *Dose;
    } else {			/* same Subject */
      if (!is_na_DOUBLE(Dose)) { /* Dose measurement */
	mm++;
	tl[mm] = *Time;
	ds[mm] = *Dose;
      } else {			/* Concentration measurement */
	for(j = 0; j <= mm; j++) {
	  *Resp += ds[j] * exp(-cl * (*Time - tl[j]) / v) / v;
	}
      }
    }
  }
  Free(ds); Free(tl);
}