title: How to do a fit with gnuplot using data with error in x and y?
body: <p>How to do a fit with data like x y deltax delta y? I have to do a linear fit weighted to the error in both axis what is the exact syntax?</p>
  
  <p>Fit <code>f (x)  "file.txt" u1:2:3:4</code> via <code>a</code>, <code>b</code> with <code>xyerrorbars</code>.</p>
  
  <pre><code>f (x) =a*x + b
  </code></pre>
  
  <p>Result: singular matrix in invert_RtR</p>