/*  Quinidine model  */
/* loop for each row */
/* if interval not NA, use steady state model */
/* if dose record and interval missing , conc for serum and abs compartment equations */
/* use C and Ca in *resp */
void 
nlme_one_comp_open (longint *nrow, double *Resp, double *inmat)
{
  longint i, nn = *nrow;
  double ke, ka, tl = 0, delta, C, Ca, interval,
    *Subject, *Time, *Conc, *Dose, *Interval, *V, *Ka, *Ke,
         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;
  Conc = inmat + 2 * nn;
  Dose = inmat + 3 * nn;
  Interval = inmat + 4 * nn;
  V = inmat + 5 * nn;
  Ka = inmat + 6 * nn;
  Ke = inmat + 7 * nn;
  for(i = nn; i--; Resp++, Subject++, Time++, Conc++, Dose++,
                   Interval++, V++, Ka++, Ke++) {
    ke = *Ke; ka = *Ka;
    if (*Subject != sl) {	/* new Subject */
      sl = *Subject;
      tl = *Time;
      *Resp = 0;
      if (!is_na_DOUBLE(Interval)) {		/* steady-state dosing */
	interval = *Interval;
	C = *Dose * ka * (1/(1 - exp(-ke * interval)) -
			  1/(1 - exp(-ka * interval)))/
			    (*V * (ka - ke));
	Ca = *Dose / (*V * (1 - exp(-ka * interval)));
      } else {			/* non-steady-state */
	C = 0;
	Ca = *Dose/ *V;
      }
    } else {			/* same Subject */
      if (!is_na_DOUBLE(Dose)) {
	if (!is_na_DOUBLE(Interval)) {	/* steady-state dosing */
	  interval = *Interval;
	  C = *Dose * ka * (1/(1 - exp(-ke * interval)) -
			    1/(1 - exp(-ka * interval)))/
			      (*V * (ka - ke));
	  Ca = *Dose / (*V * (1 - exp(-ka * interval)));
	} else {		/* non-steady-state */
	  delta = *Time - tl;
	  C = C*exp(-ke * delta) +
	    Ca*ka*(exp(-ke*delta) - exp(-ka*delta))/(ka -ke);
	  Ca = Ca * exp(-ka*delta) + *Dose / *V;
	}
	tl = *Time;
	*Resp = 0;
      } else if (!is_na_DOUBLE(Conc)) {
	delta = *Time - tl;
	*Resp = C * exp(-ke * delta) + Ca * ka *
	  (exp(-ke * delta) - exp(-ka * delta))/(ka - ke);
      } else *Resp = 0;
    }
  }
}