title: Correlation coefficient on gnuplot
body: <p>I want to plot data using fit function : <code>function f(x) = a+b*x**2</code>. After ploting i have this result: </p>
  
  <pre><code>correlation matrix of the fit parameters:
  
                 m      n      
  m               1.000 
  n              -0.935  1.000 
  </code></pre>
  
  <p>My question is : how can i found a correlation coefficient on gnuplot ?</p>