Add preconditioner to DescentMinimizer interface

nifty5/minimization/descent_minimizers.py

@@ -43,7 +43,7 @@ class DescentMinimizer(Minimizer):
         self._controller = controller
         self.line_searcher = line_searcher
 
-    def __call__(self, energy):
+    def __call__(self, energy, preconditioner=None):
         """Performs the minimization of the provided Energy functional.
 
         Parameters
@@ -79,7 +79,7 @@ class DescentMinimizer(Minimizer):
 
             # compute a step length that reduces energy.value sufficiently
             new_energy, success = self.line_searcher.perform_line_search(
-                energy=energy, pk=self.get_descent_direction(energy),
+                energy=energy, pk=self.get_descent_direction(energy, preconditioner),
                 f_k_minus_1=f_k_minus_1)
             if not success:
                 self.reset()