Use momentum indicator to evaluate a Support/Resistance line?

Here's some regression code I wrote a while ago. You add values in a linear series using the $regression->add($price) function.

Calling $regression->pos($xPos) returns the price of the linear regression at that position. Should be fairly simple to compute the difference of price from regression @ $xPos.

PHP:

    class Regression {
        protected $aVal, $bVal;
        protected $tableR, $tableT;
   
        public function __construct() {
            $this->reset();
        }
   
        public function update() {
            if (count($this->tableR) < 10)
                return;
       
            $n = count($this->tableR);
       
            //Offset of the linear regression
            $this->aVal = (($this->tableT['y']*$this->tableT['x2'])-($this->tableT['x']*$this->tableT['xy']))
                                /*    ----------------------- */ / /*    ----------------------- */
                                     (($n*$this->tableT['x2'])-pow($this->tableT['x'],2));
       
            //Gradient of the linear regression
            $this->bVal = (($n*$this->tableT['xy'])-($this->tableT['x']*$this->tableT['y']))
                            /*    ----------------------- */ / /*    ----------------------- */
                                  (($n*$this->tableT['x2'])-pow($this->tableT['x'],2));
        }
   
        public function reset() {
            $this->tableT = array('x' => 0, 'y' => 0, 'xy' => 0, 'x2' => 0, 'y2' => 0);
            $this->tableR = array();
        }

        public function add($value, $update=TRUE) {
            $row = array();
            $row['x'] = count($this->tableR)+1;
            $row['y'] = $value;
            $row['xy'] = $row['x']*$row['y'];
            $row['x2'] = pow($row['x'], 2);
            $row['y2'] = pow($row['y'], 2);
       
            foreach ($row as $key => $value)
                $this->tableT[$key] += $value;
       
            $this->tableR[] = $row;
   
            if ($update) $this->update();
        }
   
        public function add_array(array $values) {
            foreach ($values as $value)
                $this->add($value, FALSE);
            $this->update();
        }
   
        public function pos($x) {
            return $this->aVal + ($this->bVal * $x);
        }
   
        public function std_dev() {
            $mean = 0;
            foreach ($this->tableR as $set)
                $mean += $set['y'];
            $mean /= count($this->tableR);
       
            $sum = 0;
            foreach ($this->tableR as $set)
                $sum += pow($set['y'] - $mean, 2);
       
            return sqrt($sum / (count($this->tableR)-1));
        }
   
        public function a_val() { return (isset($this->aVal)) ? $this->aVal : FALSE; }
        public function b_val() { return (isset($this->bVal)) ? $this->bVal : FALSE; }
    }

https://github.com/tavurth/SimpleRegression