srecord noeq SmoothedMovingAverage(double period) {
  selfType period(double period) { this.period = period; this; }
  
  gettable double value = Double.NaN;
  gettable long steps;
  
  double get() { ret value; }
  
  double add(double x) {
    ++steps;
    if (isNaN(value))
      value = x;
    else
      value = blend(value, x, alpha());
    ret value;
  }
  
  double alpha() {
    ret reciprocal(period);
  }
  
  void reset {
    resetFields(this, "steps value");
  }
  
  bool complete() {
    ret steps >= period;
  }
}

Began life as a copy of #1036438