 structured grid</h2>

<p>WHAT THIS EXAMPLE DEMONSTRATES:</p>
<ul>
  <li>Handling a 2d structured grid</li>
  <li>Using the nonlinear solvers</li>
  <li>Changing the default linear solver</li>
</ul>

<p>FURTHER DETAILS:</p>
<ul>
  <li><a href="https://www.mcs.anl.gov/petsc/petsc-current/src/snes/tutorials/ex19.c.html#line19">Mathematical description of the problem</a></li>
  <li><a href="https://www.mcs.anl.gov/petsc/petsc-current/src/snes/tutorials/ex19.c.html#line94">main program source code</a></li>
  <l