title: pseudo-arc length continuation petsc4py
body: <p>I have been a user of pseudo arc-length continuation, nonlinear solvers... in Trilinos LOCA (c++) for years but I recently come across the python package petsc4py. This simplified a lot my programming for a minor decrease in speed. </p>
  
  <p>The only missing class of petsc4py is a pseudo-arclength continuation solver. PETSC has a pseudo-time stepper solver but this is not nearly as useful as turning points break down the algorithm.</p>
  
  <p>Trilinos LOCA has a wrapper for PETSC but I was looking for a solution where the problem is specified in python (from petsc4py) rather than in c or c++.</p>
  
  <p>Hence, I am looking for a class written in petsc4py, or callable from petsc4py, implementing pseudo-arclength continuation.</p>
  
  <p>Thank your very much.  </p>