title: Gnuplot: imposing bounds on fitting parameters
body: <p>Is there a way to contraint the values that fitting parameters can take with gnuplot?</p>
  
  <pre><code>f(x) = A/(x**2) + B/(x**4)
  A = 1
  B = 0.01
  fit f(x) 'data.dat' u 1:2 via A,B
  </code></pre>
  
  <p>I know that <code>B &lt; 0</code> doesn't make any sense. Is there a way to impose <code>B &gt; 0</code>?</p>