2 <span class="comment">%  'deriv' Derivative estimation. 'deriv',1 specifies the first derivative</span>
0103 <span class="comment">%         (or more correctly, an estimate of the local slope is returned.</span>
0104 <span class="comment">%         'deriv',[1 1] specifies the second derivative. For bivariate fits</span>
0105 <span class="comment">%         'deriv',2 specifies the first partial derivative wrt x2.</span>
0106 <span class="comment">%         'deriv',[1 2] is mixed second-order derivative