diff --git a/src/Calc/Calc.php b/src/Calc/Calc.php
new file mode 100644
index 0000000..f1ee69d
--- /dev/null
+++ b/src/Calc/Calc.php
@@ -0,0 +1,78 @@
+<?php
+/**
+ * Created by PhpStorm.
+ * User: thomas
+ * Date: 16.04.18
+ * Time: 14:00
+ */
+
+namespace PSC\Library\Calc\Calc;
+
+use PSC\Library\Calc\Article;
+use PSC\Library\Calc\Engine;
+use PSC\Library\Calc\General\Type\Edge;
+use PSC\Library\Calc\General\Type\EdgeCollection;
+use PSC\Library\Calc\Option\Type\Base;
+
+class Calc
+{
+    /** @var Engine */
+    protected $engine = null;
+
+    /** @var Article */
+    protected $article = null;
+
+    protected $storageFormulas = [];
+
+    protected $storageCalcValues = [];
+
+    protected $formelCalc = null;
+
+    /**
+     * Calc constructor.
+     * @param Engine $engine
+     * @param Article $article
+     */
+    public function __construct($engine, $article)
+    {
+        $this->engine = $engine;
+        $this->article = $article;
+        $this->formelCalc = new Formel($engine, $article);
+    }
+
+    public function calc()
+    {
+        $price = 0;
+
+        /** @var Base $option */
+        foreach($this->article->getOptions() as $option) {
+
+            /** @var EdgeCollection $collection */
+            foreach($option->getEdgesCollectionContainer() as $collection) {
+
+                if($collection->getFormel() != "") {
+                    $formel = $this->formelCalc->parseVariables($collection->getFormel());
+                    eval('$var = ' . $formel . ';');
+                }else{
+                    $var = $this->engine->getVariables()[$collection->getName()];
+                }
+
+                /** @var Edge $edge */
+                foreach($collection as $edge) {
+
+                    if($edge->isValid($var)) {
+                        $formel = $this->formelCalc->parseVariables($edge->getFormel());
+                        if ($formel != "") {
+                            eval('$price += ' . $formel . ';');
+
+                            $this->engine->setVariable('price', $price);
+                        }
+                    }
+                }
+            }
+        }
+
+        return $price;
+    }
+
+}
\ No newline at end of file
diff --git a/src/Calc/EvalCommand.php b/src/Calc/EvalCommand.php
new file mode 100644
index 0000000..c387ec4
--- /dev/null
+++ b/src/Calc/EvalCommand.php
@@ -0,0 +1,54 @@
+<?php
+/**
+ * Created by PhpStorm.
+ * User: thomas
+ * Date: 13.04.18
+ * Time: 22:38
+ */
+
+namespace PSC\Library\Calc\Calc;
+
+
+class EvalCommand
+{
+    public function calc($formel) {
+        $result = 0;
+
+        eval('$result += ' . $formel . ';');
+
+        return $result;
+    }
+
+    private function parseVariables($formel)
+    {
+        preg_match_all('/\$V\w*\$V/', $formel, $founds);
+
+        $variables = $this->engine->getVariables();
+
+        if (!empty($founds [0])) {
+            foreach ($founds [0] as $key => $found) {
+                $foundvalue = str_replace('$V', '', $found);
+                if (isset($variables [$foundvalue])) {
+                    if ($variables [$foundvalue] == 'null') {
+                        $formel = str_replace($found, 0, $formel);
+                    } else {
+                        if ($foundvalue == 'auflage') {
+                            $formel = str_replace($found, str_replace(',', '.', $variables [$foundvalue]), $formel);
+                        } else {
+                            if ($variables [$foundvalue] == '') {
+                                $formel = str_replace($found, 0, $formel);
+                            } else {
+                                $formel = str_replace($found, $variables [$foundvalue], $formel);
+                            }
+                        }
+                    }
+                } else {
+                    $formel = str_replace($found, 0, $formel);
+                }
+            }
+        }
+
+        return $formel;
+    }
+
+}
\ No newline at end of file
diff --git a/src/Calc/Formel.php b/src/Calc/Formel.php
index 5e7ac9c..58b0f64 100644
--- a/src/Calc/Formel.php
+++ b/src/Calc/Formel.php
@@ -17,40 +17,18 @@ class Formel
     /** @var Article */
     protected $article = null;
 
+    /**
+     * Calc constructor.
+     * @param Engine $engine
+     * @param Article $article
+     */
     public function __construct($engine, $article)
     {
         $this->engine = $engine;
         $this->article = $article;
     }
 
-    /**
-     * @return float
-     */
-    public function calc()
-    {
-        $price = 0;
-
-        /** @var Base $option */
-        foreach($this->article->getOptions() as $option) {
-
-            /** @var EdgeCollection $collection */
-            foreach($option->getEdgesCollectionContainer() as $collection) {
-                /** @var Edge $edge */
-                foreach($collection as $edge) {
-                    if($this->edgeIsValid($collection->getName(), $edge)) {
-                        $formel = $this->parseVar($edge->getFormel());
-                        if ($formel != "") {
-                            eval('$price += ' . $formel . ';');
-                        }
-                    }
-                }
-            }
-        }
-
-        return $price;
-    }
-
-    private function parseVar($formel)
+    public function parseVariables($formel)
     {
         preg_match_all('/\$V\w*\$V/', $formel, $founds);
 
@@ -81,35 +59,4 @@ class Formel
 
         return $formel;
     }
-
-    /**
-     * @param $section
-     * @param Edge $edge
-     * @return bool
-     */
-    private function edgeIsValid($section, $edge)
-    {
-        if(!isset($this->engine->getVariables()[$section])) {
-            return false;
-        }
-
-
-        if($edge->isRegion() &&
-            $edge->getFrom() <= $this->engine->getVariables()[$section] &&
-            $edge->getTo() >= $this->engine->getVariables()[$section]) {
-            return true;
-        }
-
-        if($edge->isRegion() &&
-            $edge->getFrom() <= $this->engine->getVariables()[$section] &&
-            $edge->getTo() == 0) {
-            return true;
-        }
-
-        if(!$edge->isRegion() && in_array($this->engine->getVariables()[$section], $edge->getValues())) {
-            return true;
-        }
-
-        return false;
-    }
 }
\ No newline at end of file
diff --git a/src/Engine.php b/src/Engine.php
index 1aff32b..5370526 100644
--- a/src/Engine.php
+++ b/src/Engine.php
@@ -2,7 +2,7 @@
 namespace PSC\Library\Calc;
 
 use Doctrine\Common\Persistence\ObjectRepository;
-use PSC\Library\Calc\Calc\Formel;
+use PSC\Library\Calc\Calc\Calc;
 use PSC\Library\Calc\Calc\Valid;
 use PSC\Library\Calc\Option\Type\Base;
 use PSC\Library\Calc\Option\Type\Text;
@@ -31,6 +31,9 @@ class Engine
     /** @var array */
     protected $variables = array();
 
+    /** @var array */
+    protected $calcVariables = array();
+
     /** @var float */
     protected $price = 0;
 
@@ -85,7 +88,7 @@ class Engine
     public function getArticleByName($name = false)
     {
         if($name === false) {
-            throw new \Exception('No Name provided');
+            $this->articles[0];
         }
 
         /** @var Article $article */
@@ -95,10 +98,6 @@ class Engine
                 return $article;
             }
         }
-
-        if($name === false) {
-            throw new \Exception('Article not found: ' . $name);
-        }
     }
 
     /**
@@ -207,8 +206,7 @@ class Engine
         $calcValid->calc();
 
         // CALC Formel
-
-        $calcFormel = new Formel($this, $article);
+        $calcFormel = new Calc($this, $article);
         $this->price += $calcFormel->calc();
 
         $this->dirty = false;
@@ -234,4 +232,25 @@ class Engine
         $this->price = $price;
     }
 
+    /**
+     * @return array
+     */
+    public function getCalcVariables()
+    {
+        return $this->calcVariables;
+    }
+
+    /**
+     * @param array $calcVariables
+     */
+    public function setCalcVariables($calcVariables)
+    {
+        $this->calcVariables = $calcVariables;
+    }
+
+    public function setVariable($var, $value)
+    {
+        $this->variables[$var] = $value;
+    }
+
 }
\ No newline at end of file
diff --git a/src/General/Parser/EdgeCollection.php b/src/General/Parser/EdgeCollection.php
index 93c6905..0822860 100644
--- a/src/General/Parser/EdgeCollection.php
+++ b/src/General/Parser/EdgeCollection.php
@@ -27,6 +27,10 @@ class EdgeCollection
     {
         $collection = new \PSC\Library\Calc\General\Type\EdgeCollection();
 
+        if(isset($this->node->attributes()->formel)) {
+            $collection->setFormel((string)$this->node->attributes()->formel);
+        }
+
         foreach($this->node->grenze as $row) {
             $edgeParser = new Edge($row);
             $edge = $edgeParser->parse();
diff --git a/src/General/Type/Edge.php b/src/General/Type/Edge.php
index f2a6aa3..677af9a 100644
--- a/src/General/Type/Edge.php
+++ b/src/General/Type/Edge.php
@@ -143,4 +143,29 @@ class Edge
     }
 
 
+    /**
+     * @param $value
+     * @return bool
+     */
+    public function isValid($value)
+    {
+
+        if($this->isRegion() &&
+            $this->getFrom() <= $value &&
+            $this->getTo() >= $value) {
+            return true;
+        }
+
+        if($this->isRegion() &&
+            $this->getFrom() <= $value &&
+            $this->getTo() == 0) {
+            return true;
+        }
+
+        if(!$this->isRegion() && in_array($value, $this->getValues())) {
+            return true;
+        }
+
+        return false;
+    }
 }
\ No newline at end of file
diff --git a/src/General/Type/EdgeCollection.php b/src/General/Type/EdgeCollection.php
index 0272eb6..c3d72cc 100644
--- a/src/General/Type/EdgeCollection.php
+++ b/src/General/Type/EdgeCollection.php
@@ -5,7 +5,9 @@ namespace PSC\Library\Calc\General\Type;
 class EdgeCollection extends \ArrayIterator
 {
 
-    public $name = '';
+    protected $name = '';
+
+    protected $formel = '';
 
     /**
      * @return string
@@ -23,5 +25,21 @@ class EdgeCollection extends \ArrayIterator
         $this->name = $name;
     }
 
+    /**
+     * @return string
+     */
+    public function getFormel()
+    {
+        return $this->formel;
+    }
+
+    /**
+     * @param string $formel
+     */
+    public function setFormel($formel)
+    {
+        $this->formel = $formel;
+    }
+
 
 }
\ No newline at end of file
diff --git a/src/Option/Parser.php b/src/Option/Parser.php
index 4311899..ec3db1b 100644
--- a/src/Option/Parser.php
+++ b/src/Option/Parser.php
@@ -1,6 +1,7 @@
 <?php
 namespace PSC\Library\Calc\Option;
 
+use PSC\Library\Calc\Option\Parser\Hidden;
 use PSC\Library\Calc\Option\Parser\Input;
 use PSC\Library\Calc\Option\Parser\Select;
 use PSC\Library\Calc\Option\Parser\Text;
@@ -30,6 +31,9 @@ class Parser
             case 'text':
                 $obj = new Text($node);
                 break;
+            case 'hidden':
+                $obj = new Hidden($node);
+                break;
         }
 
         return $obj;
diff --git a/src/Option/Parser/Hidden.php b/src/Option/Parser/Hidden.php
new file mode 100644
index 0000000..1e48601
--- /dev/null
+++ b/src/Option/Parser/Hidden.php
@@ -0,0 +1,29 @@
+<?php
+namespace PSC\Library\Calc\Option\Parser;
+
+use PSC\Library\Calc\General\Parser\EdgeCollectionContainer;
+
+class Hidden extends Base
+{
+
+    protected $element;
+
+    public function __construct(\SimpleXMLElement $node)
+    {
+        $this->element = new \PSC\Library\Calc\Option\Type\Hidden();
+        parent::__construct($node);
+    }
+
+    public function parse()
+    {
+        parent::parse();
+
+        if($this->node->children()) {
+            $edgeCollectionContainerParser = new EdgeCollectionContainer($this->node);
+            $this->element->setEdgesCollectionContainer($edgeCollectionContainerParser->parse());
+        }
+
+        return $this->element;
+    }
+
+}
\ No newline at end of file
diff --git a/src/Option/Type/Hidden.php b/src/Option/Type/Hidden.php
new file mode 100644
index 0000000..83b8be5
--- /dev/null
+++ b/src/Option/Type/Hidden.php
@@ -0,0 +1,9 @@
+<?php
+namespace PSC\Library\Calc\Option\Type;
+
+class Hidden extends Base
+{
+
+    static public $type = 'hidden';
+
+}
\ No newline at end of file
diff --git a/tests/Calc/PriceMinTest.php b/tests/Calc/PriceMinTest.php
new file mode 100644
index 0000000..0057c92
--- /dev/null
+++ b/tests/Calc/PriceMinTest.php
@@ -0,0 +1,53 @@
+<?php
+namespace PSC\Library\Calc\Tests\Calc;
+
+use PSC\Library\Calc\Article;
+use PSC\Library\Calc\Engine;
+use PSC\Library\Calc\Option\Type\Base;
+use PSC\Library\Calc\PaperContainer\Container;
+
+class PriceMinTest extends \PHPUnit_Framework_TestCase
+{
+    /** @var Engine */
+    protected $engine = null;
+
+    public function setUp()
+    {
+        $this->engine = new Engine(new Container());
+        $this->engine->loadString(file_get_contents(__DIR__ . '/../TestFiles/Calc/price_min.xml'));
+
+    }
+
+    public function tearDown()
+    {
+        $this->engine = null;
+    }
+
+    public function testIfArticleCountIsCorrect()
+    {
+        $this->assertEquals(1, $this->engine->getArticles()->Count());
+    }
+
+    public function testIfParserGetMinPrice()
+    {
+        $this->engine->calc();
+
+        $this->assertEquals(2500, $this->engine->getPrice());
+    }
+
+    public function testIfCalcReturnsGrenzeWithFormular()
+    {
+        $this->engine->setVariables([
+            'gebwert' => 1000000,
+            'maschwertjuengerfuenf' => 400000,
+            'maschwertaelterfuenf' => 400000,
+            'allegereate' => 400000,
+            'betriebsunterbrechung' => 400000,
+            'umsatzjahrtransport' => 300000,
+            'umsatzjahrbh' => 400000]);
+        $this->engine->calc();
+
+        $this->assertEquals(2721.40, $this->engine->getPrice());
+    }
+
+}
\ No newline at end of file
diff --git a/tests/TestFiles/Calc/price_min.xml b/tests/TestFiles/Calc/price_min.xml
new file mode 100644
index 0000000..692a097
--- /dev/null
+++ b/tests/TestFiles/Calc/price_min.xml
@@ -0,0 +1,67 @@
+<?xml version="1.0" encoding="utf-8"?>
+<kalkulation>
+
+    <artikel>
+        <name>test1</name>
+        <kommentar>test2</kommentar>
+
+        <option id="gebyn" name="Benutzen Sie ein eigenes Gebäude?" type="Select" default="1">
+            <opt id="1" name="Ja">
+            </opt>
+            <opt id="2" name="Nein">
+            </opt>
+        </option>
+
+        <option id="gebwert" name="Bitte geben Sie den Neuwert Ihres Gebäudes/Ihrer Gebäude ein (in Euro gerundet auf Tsd.)" type="Input" default="20000" require="true" hidden="false">
+            <gebyn>
+                <grenze formel="$Vgebwert$V/1000*0.906">1</grenze>
+                <grenze formel="">2</grenze>
+            </gebyn>
+        </option>
+
+
+        <option id="maschwertjuengerfuenf" name="Bitte addieren Sie den Wert aller in Ihrem Unternehmen eingesetzten stationären Maschinen, die&#160;&lt;b&gt;jünger als fünf Jahre&lt;/b&gt;&#160;sind (in Euro gerundet auf Tsd.)." type="Input" default="0" require="true" hidden="false">
+            <gebyn>
+                <grenze formel="$Vmaschwertjuengerfuenf$V/1000*0.900">1</grenze>
+            </gebyn>
+        </option>
+
+        <option id="maschwertaelterfuenf" name="Bitte addieren Sie den Wert aller in Ihrem Unternehmen eingesetzten stationären Maschinen, die&#160;&lt;b&gt;älter als fünf Jahre&lt;/b&gt;&#160;sind. (in Euro gerundet auf Tsd.)" type="Input" default="0" require="true" hidden="false">
+            <gebyn>
+                <grenze formel="$Vmaschwertaelterfuenf$V/1000*1.350">1-</grenze>
+            </gebyn>
+        </option>
+
+        <option id="allegereate" name="Bitte addieren Sie den Wert aller in Ihrem Unternehmen eingesetzten elektronischen Geräte, Vorräte und sonstigen Wertgegenstände, die von Bedeutung sind. (in Euro gerundet auf Tsd.)" type="Input" default="0" require="true" hidden="false">
+            <gebyn>
+                <grenze formel="$Vallegereate$V/1000*0.971">1-</grenze>
+            </gebyn>
+        </option>
+
+        <option id="betriebsunterbrechung" name="Zur Berechnung des Versicherungsschutzes für die Betriebsunterbrechung verdoppeln Sie bitte den Gesamtumsatz des vergangenen Jahres und tragen Sie den Wert in das vorgegebene Feld ein. (in Euro gerundet auf Tsd.)" type="Input" default="0" require="true" hidden="false">
+            <gebyn>
+                <grenze formel="$Vbetriebsunterbrechung$V/1000*0.590">1-</grenze>
+            </gebyn>
+        </option>
+
+        <option id="umsatzjahrtransport" name="Zur Berechnung des Versicherungsschutzes für die Transportversicherung tragen Sie bitte den Gesamtumsatz des vergangenen Jahres ein. (in Euro gerundet auf Tsd.)" type="Input" default="0" require="true" hidden="false">
+            <gebyn>
+                <grenze formel="$Vumsatzjahrtransport$V/1000*0.250">1-</grenze>
+            </gebyn>
+        </option>
+
+        <option id="umsatzjahrbh" name="Zur Berechnung des Versicherungsschutzes für die Betriebshaftpflichtversicherung tragen Sie bitte den Gesamtumsatz des vergangenen Jahres ein. (in Euro gerundet auf Tsd.)" type="Input" default="0" require="true" hidden="false">
+            <gebyn>
+                <grenze formel="$Vumsatzjahrbh$V/1000*0.540">1-</grenze>
+            </gebyn>
+        </option>
+
+        <option id="calc_min" name="" type="Hidden">
+            <gebyn formel="$Vprice$V &lt;= 2500? 1:2">
+                <grenze formel="2500-$Vprice$V">1</grenze>
+                <grenze formel="">2</grenze>
+            </gebyn>
+        </option>
+
+    </artikel>
+</kalkulation>
\ No newline at end of file