 class="Other">:</span> <span class="Identifier">cdouble</span> <span class="Comment">## NOTE: the user may set the value explicitly; OR, if the passed</span>
                 <span class="Comment">##     value is zero, then the &quot;Default&quot; value will be substituted by</span>
                 <span class="Comment">##     mpfit().</span>
                 <span class="Comment">## Relative chi-square convergence criterium Default: 1e-10</span>
  <span class="Identifier">xtol</span><span class="Operator