title: What good libraries are there for solving a system of non-linear equations in C++?
body: <p>In a C++ application I'm coding, I need to solve a system of <strong>non</strong>-linear equations (N equations, N unknowns).</p>
  
  <p>The systems I'm solving will be rather small (up to 10 equations/unknowns), so performance is not going to be a real issue.
  I've searched the web a bit for a non-linear solver library, and I couldn't get to something which looks easy to use (got to <em>NOX</em> and <a href="http://devernay.free.fr/hacks/cminpack/cminpack.html" rel="noreferrer">C/C++ Minpack</a>, but both seem to be an overkill for my need).</p>
  
  <p>Any thoughts and ideas of easy-to-use libraries for this purpose?</p>