added backward difference methods, updated documentation, updated tests

Author: tamaskis

INSTALL/Numerical Differentiation Toolbox.mltbx

@@ -75,7 +75,7 @@
           <td style="text-align:center"><b>Variable</b></td>
           <td style="text-align:center"><b>Symbol</b></td>
           <td style="text-align:center"><b>Description</b></td>
-          <td style="text-align:center"><b>Format</b></td>
+          <td style="text-align:center"><b>Format</b></td>f
       </tr>
       <tr>
           <td rowspan="3" style="text-align:center"><b>Input</b></td>
@@ -132,7 +132,7 @@
    -0.0042
    -0.0027
 
-</pre><h2 id="8">See also</h2><p><a href="partial2_doc.html"><tt>partial2</tt></a> | <a href="gradient2_doc.html"><tt>gradient2</tt></a> | <a href="directional2_doc.html"><tt>directional2</tt></a> | <a href="jacobian2_doc.html"><tt>jacobian2</tt></a> |</p><p class="footer"><br><a href="https://www.mathworks.com/products/matlab/">Published with MATLAB&reg; R2021b</a><br></p></div><!--
+</pre><h2 id="8">See also</h2><p><a href="partial2_doc.html"><tt>partial2</tt></a> | <a href="gradient2_doc.html"><tt>gradient2</tt></a> | <a href="directional2_doc.html"><tt>directional2</tt></a> | <a href="jacobian2_doc.html"><tt>jacobian2</tt></a></p><p class="footer"><br><a href="https://www.mathworks.com/products/matlab/">Published with MATLAB&reg; R2021b</a><br></p></div><!--
 ##### SOURCE BEGIN #####
 %% |derivative2|
 % Derivative of a univariate, scalar or vector-valued function using the backward difference approximation (given two points).
@@ -151,7 +151,7 @@
 %           <td style="text-align:center"><b>Variable</b></td>
 %           <td style="text-align:center"><b>Symbol</b></td>
 %           <td style="text-align:center"><b>Description</b></td>
-%           <td style="text-align:center"><b>Format</b></td>
+%           <td style="text-align:center"><b>Format</b></td>f
 %       </tr>
 %       <tr>
 %           <td rowspan="3" style="text-align:center"><b>Input</b></td>
@@ -215,6 +215,6 @@
 % <partial2_doc.html |partial2|> | 
 % <gradient2_doc.html |gradient2|> | 
 % <directional2_doc.html |directional2|> | 
-% <jacobian2_doc.html |jacobian2|> | 
+% <jacobian2_doc.html |jacobian2|>
 ##### SOURCE END #####
 --></body></html>