remove fixed point magic

nifty/field.py

@@ -608,39 +608,11 @@ class Field(Loggable, Versionable, object):
 
         # correct variance
         if preserve_gaussian_variance:
+            assert issubclass(val.dtype.type, np.complexfloating),\
+                    "complex input field is needed here"
             h *= np.sqrt(2)
             a *= np.sqrt(2)
 
-            if not issubclass(val.dtype.type, np.complexfloating):
-                # in principle one must not correct the variance for the fixed
-                # points of the hermitianization. However, for a complex field
-                # the input field loses half of its power at its fixed points
-                # in the `hermitian` part. Hence, here a factor of sqrt(2) is
-                # also necessary!
-                # => The hermitianization can be done on a space level since
-                # either nothing must be done (LMSpace) or ALL points need a
-                # factor of sqrt(2)
-                # => use the preserve_gaussian_variance flag in the
-                # hermitian_decomposition method above.
-
-                # This code is for educational purposes:
-                fixed_points = [domain[i].hermitian_fixed_points()
-                                for i in spaces]
-                fixed_points = [[fp] if fp is None else fp
-                                for fp in fixed_points]
-
-                for product_point in itertools.product(*fixed_points):
-                    slice_object = np.array((slice(None), )*len(val.shape),
-                                            dtype=np.object)
-                    for i, sp in enumerate(spaces):
-                        point_component = product_point[i]
-                        if point_component is None:
-                            point_component = slice(None)
-                        slice_object[list(domain_axes[sp])] = point_component
-
-                    slice_object = tuple(slice_object)
-                    h[slice_object] /= np.sqrt(2)
-                    a[slice_object] /= np.sqrt(2)
         return (h, a)
 
     def _spec_to_rescaler(self, spec, result_list, power_space_index):

nifty/spaces/rg_space/rg_space.py

@@ -100,24 +100,6 @@ class RGSpace(Space):
         self._distances = self._parse_distances(distances)
         self._zerocenter = self._parse_zerocenter(zerocenter)
 
-    def hermitian_fixed_points(self):
-        dimensions = len(self.shape)
-        mid_index = np.array(self.shape)//2
-        ndlist = [1]*dimensions
-        for k in range(dimensions):
-            if self.shape[k] % 2 == 0:
-                ndlist[k] = 2
-        ndlist = tuple(ndlist)
-        fixed_points = []
-        for index in np.ndindex(ndlist):
-            for k in range(dimensions):
-                if self.shape[k] % 2 != 0 and self.zerocenter[k]:
-                    index = list(index)
-                    index[k] = 1
-                    index = tuple(index)
-            fixed_points += [tuple(index * mid_index)]
-        return fixed_points
-
     def hermitianize_inverter(self, x, axes):
         # calculate the number of dimensions the input array has
         dimensions = len(x.shape)

nifty/spaces/space/space.py

@@ -161,19 +161,6 @@ class Space(DomainObject):
         raise NotImplementedError(
             "There is no generic co-smoothing kernel for Space base class.")
 
-    def hermitian_fixed_points(self):
-        """ Returns the array points which remain invariant under the action
-        of `hermitianize_inverter`
-
-
-        Returns
-        -------
-        list of index-tuples
-            The list contains the index-coordinates of the invariant points.
-
-        """
-        return None
-
     def hermitianize_inverter(self, x, axes):
         """ Inverts/flips x in the context of Hermitian decomposition.
 

test/test_field.py

@@ -67,6 +67,8 @@ class Test_Functionality(unittest.TestCase):
         r2 = RGSpace(s2, harmonic=True, zerocenter=(z2,))
         ra = RGSpace(s1+s2, harmonic=True, zerocenter=(z1, z2))
 
+        if preserve:
+            complexdata=True
         v = np.random.random(s1+s2)
         if complexdata:
             v = v + 1j*np.random.random(s1+s2)

test/test_spaces/test_lm_space.py

@@ -127,7 +127,3 @@ class LMSpaceFunctionalityTests(unittest.TestCase):
     def test_distance_array(self, lmax, expected):
         l = LMSpace(lmax)
         assert_almost_equal(l.get_distance_array('not').data, expected)
-
-    def test_hermitian_fixed_points(self):
-        x = LMSpace(5)
-        assert_equal(x.hermitian_fixed_points(), None)

test/test_spaces/test_rg_space.py

@@ -190,8 +190,3 @@ class RGSpaceFunctionalityTests(unittest.TestCase):
         assert_almost_equal(res, expected)
         if inplace:
             assert_(x is res)
-
-    def test_hermitian_fixed_points(self):
-        x = RGSpace((5, 6, 5, 6), zerocenter=[False, False, True, True])
-        assert_equal(x.hermitian_fixed_points(),
-                     [(0, 0, 2, 0), (0, 0, 2, 3), (0, 3, 2, 0), (0, 3, 2, 3)])