Fixed a bug with spaces vs. axes. in FFTOperator.

nifty/operators/fft_operator/fft_operator.py

@@ -40,7 +40,8 @@ class FFTOperator(LinearOperator):
     def _times(self, x, spaces, types):
         spaces = utilities.cast_axis_to_tuple(spaces, len(x.domain))
 
-        new_val = self._forward_transformation.transform(x.val, axes=spaces)
+        axes = x.domain_axes[spaces[0]]
+        new_val = self._forward_transformation.transform(x.val, axes=axes)
 
         if spaces is None:
             result_domain = self.target
@@ -56,7 +57,8 @@ class FFTOperator(LinearOperator):
     def _inverse_times(self, x, spaces, types):
         spaces = utilities.cast_axis_to_tuple(spaces, len(x.domain))
 
-        new_val = self._inverse_transformation.transform(x.val, axes=spaces)
+        axes = x.domain_axes[spaces[0]]
+        new_val = self._inverse_transformation.transform(x.val, axes=axes)
 
         if spaces is None:
             result_domain = self.domain