noise.c

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#include "libtpcmodext.h"
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int noiseSD4Simulation(
  double y,
  double t1,
  double dt,
  double hl,
  double a,
  double *sd,
  char *status,
  int verbose
) {
  double d, lambda, f;
 
  if(verbose>0) printf("noiseSD4Simulation(%g, %g, %g, %g, %g, *sd, ...)\n",
                       y, t1, dt, hl, a);
  if(status!=NULL) strcpy(status, "invalid data");
  if(sd==NULL) return 1;
  if(t1<0.0) return 2;
  if(dt<=0.0) return 3;
 
  /* Decay factor (<=1) */
  if(hl<=0.0) {
    d=1.0; lambda=0.0;
  } else {
    if(status!=NULL) strcpy(status, "invalid half-life");
    lambda=hl2lambda(hl); if(lambda<0.0) return 4;
    d=hlLambda2factor(-lambda, t1, dt); if(d<0.0) return 5;
  }
  /* SD */
  f=y*d*dt;
  if(f<=0.0) *sd=0.0;
  else *sd=y*sqrt(a/f);
 
  if(status!=NULL) strcpy(status, "ok");
  return(0);
}
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int noiseSD4SimulationFromDFT(
  DFT *dft,
  int index,
  double pc,
  double *sd,
  char *status,
  int verbose
) {
  int ret, fi;
  double hl=0.0, t1, deltat;
  double *y;
  DFT mean;
 
  if(verbose>0) printf("noiseSD4SimulationFromDFT(DFT, %d, %g, sd[], ...)\n",
                       index, pc);
  if(status!=NULL) strcpy(status, "invalid data");
  if(dft==NULL || sd==NULL) return 1;
  if(dft->voiNr<1 || dft->frameNr<1) return 2;
  if(dft->voiNr>1 && index>=dft->voiNr) return 3;
 
  /* Check that valid frame times are available */
  if(status!=NULL) strcpy(status, "invalid frame times");
  for(fi=0; fi<dft->frameNr; fi++)
    if(dft->x2[fi]<=dft->x1[fi] || dft->x1[fi]<0.0) return 4;
  if(status!=NULL) strcpy(status, "missing time unit");
  if(dft->timeunit!=TUNIT_SEC && dft->timeunit!=TUNIT_MIN) return 5;
 
  /* Check if isotope is available, if it is needed */
  if(dft->decayCorrected==DFT_DECAY_CORRECTED || 
     dft->decayCorrected==DFT_DECAY_UNKNOWN)
  {
    hl=hlFromIsotope(dft->isotope);
    if(status!=NULL) strcpy(status, "missing isotope halflife");
    if(hl<=0.0) return 6;
  }
  if(verbose>1) printf("halflife := %g\n", hl);
 
  /* Set pointer to activity concentration data */
  dftInit(&mean);
  if(dft->voiNr==1) {
    y=dft->voi[0].y;
  } else if(index>=0) {
    y=dft->voi[index].y;
  } else {
    /* Compute TAC mean */
    ret=dftMeanTAC(dft, &mean); if(ret!=0) {
      if(status!=NULL) strcpy(status, "cannot calculate mean TAC");
      return 8;
    }
    /* and use that */
    y=mean.voi[0].y;
  }
 
  /* Compute SD for each sample time */
  if(pc<=0.0) pc=1.0;
  for(fi=0; fi<dft->frameNr; fi++) {
    t1=dft->x1[fi]; deltat=dft->x2[fi]-dft->x1[fi];
    if(dft->timeunit==TUNIT_SEC) {t1/=60.0; deltat/=60.0;}
    ret=noiseSD4Simulation(y[fi], t1, deltat, hl, pc, sd+fi, status, verbose);
    if(ret!=0) break;
  }
  dftEmpty(&mean);
  if(ret!=0) {
    if(status!=NULL)
      sprintf(status, "cannot calculate SD for noise simulation (%d)", ret);
    return(100+ret);
  }
 
  if(status!=NULL) strcpy(status, "ok");
  return 0;
}
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