] * y[2] - theta[2];
  return z;
}</code></pre>
<p>The function takes the unknowns we wish to solve for in <code>y</code> (a
vector), the system parameters in <code>theta</code> (a vector), the real
data in <code>x_r</code> (a real array) and the integer data in <code>x_i</code>
(an integer array). The system function returns the value of the
function (a vector), for which we want to compute the roots. Our
example does not use real or integer data. Nevertheless, these unused
arguments must be included in th