public BigDecimal getChangeFromAvg50() {
        if(this.price == null || this.priceAvg50 == null) {
            return null;
        }
        return this.price.subtract(this.priceAvg50);
    }
public BigDecimal getChangeFromAvg50 ( ) { if ( this . price == null || this . priceAvg50 == null ) { return null ; } return this . price . subtract ( this . priceAvg50 ) ; }
@return      difference between current price and 50 day moving average