ranoise.c

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#include "tpcclibConfig.h"
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#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <time.h>
#include <string.h>
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#include "tpcisotope.h"
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double noiseSD4Frame(
  double y,
  double t1,
  double dt,
  int isotope,
  double a
) {
  /* Frame start time must be >=0 and frame duration must be >0 */
  if(isnan(y) || !(t1>=0.0) || !(dt>0.0) || !(a>=0.0)) return(nan(""));
  /* If concentration is not positive, then its SD is zero */
  if(!(y>0.0)) return(0.0);
 
  /* Calculate decay factor (<=1) */
  double df;
  if(isotope==ISOTOPE_UNKNOWN) {
    df=1.0;
  } else {
    df=1.0/decayCorrectionFactorFromIsotope(isotope, t1, dt);
    if(!(df>0.0 && df<=1.0)) return(nan(""));
  }
 
  /* Calculate SD */
  return(sqrt((a*y)/(dt*df)));
}
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