persistable sclass GeometricPriceCells is PriceCells {
  // cell size in percent
  settable double cellSizeInPercent;
  
  // one of the cell limits
  settable double basePrice = 1000;
  
  *(double *cellSizeInPercent) {}
  *(double *basePrice, double *cellSizeInPercent) {}
  
  double ratio() {
    ret 1+cellSizeInPercent/100;
  }

  double toLogScale(double price) {
    ret log(price, ratio());
  }
  
  double fromLogScale(double logPrice) {
    ret pow(ratio(), logPrice);
  }

  double logBasePrice() {
    ret toLogScale(basePrice);
  }

  double remainder(double price) {
    ret remainder(toLogScale(price));
  }

  double remainderLog(double logPrice) {
    ret frac(logPrice-logBasePrice());
  }

  // TODO: fix this logic's rounding problems
  
  public bool isCellLimit(double price) {
    ret remainder(price) == 0;
  }
  
  public double nextCellLimitLog(double logPrice) {
    double r = remainderLog(logPrice);
    ret logPrice + 1-r;
  }
  
  public double nextCellLimit(double price) {
    ret fromLogScale(nextCellLimitLog(toLogScale(price)));
  }
  
  public double previousCellLimitLog(double logPrice) {
    double r = remainderLog(logPrice);
    ret logPrice - (r == 0 ? 1 : r);
  }
  
  public double previousCellLimit(double price) {
    ret fromLogScale(previousCellLimitLog(toLogScale(price)));
  }
  
  public double nCellLimitsDown(double price, int n) {
    double logPrice = toLogScale(price);
    logPrice = previousCellLimitLog(logPrice)-(n-1);
    ret fromLogScale(logPrice);
  }
  
  public double nCellLimitsUp(double price, int n) {
    double logPrice = toLogScale(price);
    logPrice = nextCellLimitLog(logPrice)+n;
    ret fromLogScale(logPrice);
  }
  
  public double priceToCellNumber(double price) {
    ret toLogScale(price)-logBasePrice();
  } 
  
  public double cellNumberToPrice(double cellNumber) {
    ret fromLogScale(cellNumber+logBasePrice());
  }
  
  toString {
    ret formatDouble2(cellSizeInPercent) + "% cells with C0=" + formatPrice(basePrice);
  }
}

Began life as a copy of #1036206