How to calculate return rate

public function probability() {
		global $_INPUT;
		$ret        = array();
		$time	    = $_INPUT['date'] && preg_match('/^\d{4}-\d{2}\-\d{2}$/', $_INPUT['date']) ? strtotime($_INPUT['date']) : strtotime('today');
		$today      = $time;          //该天时间头
		$tomorrow   = $time + 86400;  //该天时间尾
		$flag       = 1;              //是否进入比赛
		$model      = Model::getInstance('logs.fixedlog');
		$paymodel   = Model::getInstance('main.payment');
		$stats      = array();
		$num        = 0;              //连续一周回头人数
		$option     = isset($_INPUT['app']) ? intval($_INPUT['app']) : 1;
		$interval   = isset($_INPUT['period']) ? intval($_INPUT['period']) : 1; //时间区间一周
		if($option == 1) {
			for($i = 0;$i <= $interval;$i++) {
		        $res  = $model->turnround($today,$tomorrow,$flag);  //获取该天参加比赛的会员
		        $temp = array(); 
		        foreach($res as $value){
		        	$inmatch = isset($value['inmatch']) ? json_decode($value['inmatch']) : array();
		            foreach($inmatch as $val) {
		            	if(!in_array($val, $temp)) {
	                        array_unshift($temp,$val);  //去掉该天重复参加比赛会员
		            	}
		            }
		        }
		        $i==0 ? $total = count($temp) : "";     
		        $temp = array_fill_keys($temp, $i);  //把会员记录导入stats数组
		        foreach($temp as $k=>$v) {
		        	if(array_key_exists($k,$stats)) {   //如果stats数组里面存着该会员ID，则尾部追加该登陆的每日号
	                    $stats[$k] = $stats[$k].",".$v;
		        	} else {
		        		$stats[$k] = $v;
		        	}
		        }
		        $today    = $today - 86400;   //逐次改变每日号起止时间
	            $tomorrow = $tomorrow - 86400;        
		    }
			$strlen = ($interval+1)*2-1;
			foreach($stats as $v) {
				if(isset($v)) {
					strlen(trim($v)) == $strlen ? $num++ : $num;
				}		
			}
			$ret['turnround']['all']   = $stats;
			$ret['turnround']['total'] = $total;
			$ret['turnround']['stats'] = count($stats);
			$ret['turnround']['num']   = $num;
		} else {
			$res  = $model->turnround($today,$tomorrow,$flag);  //获取该天参加比赛的会员
			$temp = array(); 
	        foreach($res as $value){
	        	$inmatch = isset($value['inmatch']) ? json_decode($value['inmatch']) : array();
	            foreach($inmatch as $val) {
	            	if(!in_array($val, $temp)) {
                        array_unshift($temp,$val);  //去掉该天重复参加比赛会员
	            	}
	            }
	        }  
	        foreach($temp as $k=>$v) {
                $paystatus = $paymodel->hasCharge($v,$tomorrow,$today-1);
                isset($paystatus) && $paystatus['num']<>0 ? $num++ : "";

	        }
            $ret['payrate']['all']   = $temp;
            $ret['payrate']['total'] = count($temp);
			$ret['payrate']['num']   = $num;
		}
		return $this->ret($ret);
    }