persistable sclass GeometricPriceCells is PriceCells {
  // cell size in percent
  settable double cellSizeInPercent;
  
  // one of the cell limits
  settable double basePrice;
  
  *(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 frac(toLogScale(price)-logBasePrice());
  }

  // TODO: fix this logic's rounding problems
  
  public bool isCellLimit(double price) {
    ret remainder(price) == 0;
  }
  
  public double nextCellLimit(double price) {
    double logPrice = toLogScale(price);
    double r = remainder(price);
    logPrice += 1-r;
    ret fromLogScale(logPrice);
  }
  
  public double previousCellLimit(double price) {
    double logPrice = toLogScale(price);
    double r = remainder(price);
    logPrice -= (r == 0 ? 1 : r);
    ret fromLogScale(logPrice);
  }
  
  public double nCellLimitsDown(double price, int n) {
    double logPrice = toLogScale(price);
    logPrice = previousCellLimit(price)-(n-1);
    ret fromLogScale(logPrice);
  }
  
  public double nCellLimitsUp(double price, int n) {
    double logPrice = toLogScale(price);
    logPrice = nextCellLimit(logPrice)+n;
    ret fromLogScale(logPrice);
  }
  
}