Implemented eigen_space() in Matrix

Author: hosseinmoein

docs/HTML/DataFrame.html

@@ -1609,6 +1609,10 @@ <H2 ID="2"><font color="blue">API Reference with code samples <font size="+4">&#
       <td title="Handy date and time object">struct <a href="https://htmlpreview.github.io/?https://github.com/hosseinmoein/DataFrame/blob/master/docs/HTML/DateTime.html">DateTime</a>{}</td>
     </tr>
 
+    <tr class="item" onmouseover="this.style.backgroundColor='#ffff66';" onmouseout="this.style.backgroundColor='#d4e3e5';">
+      <td title="Matrix class">struct <a href="https://htmlpreview.github.io/?https://github.com/hosseinmoein/DataFrame/blob/master/docs/HTML/Matrix.html">Matrix</a>{}</td>
+    </tr>
+
     <tr class="item" onmouseover="this.style.backgroundColor='#ffff66';" onmouseout="this.style.backgroundColor='#d4e3e5';">
       <td title="Memory usage structure">struct <a href="https://htmlpreview.github.io/?https://github.com/hosseinmoein/DataFrame/blob/master/docs/HTML/get_memory_usage.html">MemUsage</a>{}</td>
     </tr>