Implement proper constant support 8/n

src/operators/chain_operator.py

@@ -58,7 +58,14 @@ class ChainOperator(LinearOperator):
         fct = 1.
         opsnew = []
         lastdom = ops[-1].domain
+        dtype = None
         for op in ops:
+            from .sampling_enabler import SamplingDtypeSetter
+            if isinstance(op, SamplingDtypeSetter) and isinstance(op._op, ScalingOperator):
+                if dtype is not None:
+                    raise NotImplementedError
+                dtype = op._dtype
+                op = op._op
             if (isinstance(op, ScalingOperator) and op._factor.imag == 0):
                 fct *= op._factor.real
             else:
@@ -72,7 +79,10 @@ class ChainOperator(LinearOperator):
                     break
         if fct != 1 or len(opsnew) == 0:
             # have to add the scaling operator at the end
-            opsnew.append(ScalingOperator(lastdom, fct))
+            op = ScalingOperator(lastdom, fct)
+            if dtype is not None:
+                op = SamplingDtypeSetter(op, dtype)
+            opsnew.append(op)
         ops = opsnew
         # combine DiagonalOperators where possible
         opsnew = []

test/test_energy_gradients.py

@@ -35,7 +35,6 @@ def test_gaussian(field):
     ift.extra.check_operator(energy, field)
 
 
-@pytest.mark.skip()
 def test_ScaledEnergy(field):
     icov = ift.ScalingOperator(field.domain, 1.2)
     energy = ift.GaussianEnergy(inverse_covariance=icov, sampling_dtype=np.float64)
@@ -48,6 +47,7 @@ def test_ScaledEnergy(field):
     res2 = met2(field)/0.3
     ift.extra.assert_allclose(res1, res2, 0, 1e-12)
     met1.draw_sample()
+    print(met2)
     met2.draw_sample()