added preconditioning to sampling enabler

nifty4/library/wiener_filter_curvature.py

@@ -46,7 +46,7 @@ def WienerFilterCurvature(R, N, S, inverter, sampling_inverter=None):
     """
     M = SandwichOperator.make(R, N.inverse)
     if sampling_inverter is not None:
-        op = SamplingEnabler(M, S.inverse, sampling_inverter)
+        op = SamplingEnabler(M, S.inverse, sampling_inverter, approximation=S.inverse)
     else:
         op = M + S.inverse
     return InversionEnabler(op, inverter, S.inverse)

nifty4/operators/sampling_enabler.py

@@ -50,6 +50,7 @@ class SamplingEnabler(EndomorphicOperator):
         self._likelihood = likelihood
         self._prior = prior
         self._sampling_inverter = sampling_inverter
+        self._approximation = approximation
 
     def draw_sample(self, from_inverse=False, dtype=np.float64):
         try:
@@ -60,7 +61,7 @@ class SamplingEnabler(EndomorphicOperator):
             nj = self._likelihood.draw_sample()
             energy = QuadraticEnergy(s, self._op, sp + nj,
                                      _grad=self._likelihood(s) - nj)
-            energy, convergence = self._sampling_inverter(energy)
+            energy, convergence = self._sampling_inverter(energy, preconditioner=self._approximation.inverse)
             return energy.position
 
     @property