/** * A private method to calculate the operation interval start date at the * upper bound of a range of operation intervals that require a ZIF update, * where the upper bound has been set back by the required number of * operation intervals so that current trends in differences between * forecast and actual delivery can be calculated. * * @access private * @param PEAR::Date $oDate The start date of the operation interval at the * upper bound of the operation interval range * requiring a ZIF update. * @return PEAR::Date The new upper bound date. */ function _getTrendUpperDate($oDate) { $seconds = ZONE_FORECAST_TREND_OFFSET * OX_OperationInterval::secondsPerOperationInterval(); $oDate->subtractSeconds($seconds); return $oDate; }