simplify documentation

README.md

@@ -119,7 +119,7 @@ Please acknowledge the use of NIFTy in your publication(s) by using a
 phrase such as the following:
 
 > *"Some of the results in this publication have been derived using the
-> NIFTy package [Steininger et al., 2018]."*
+> NIFTy package [Steininger et al., 2017]."*
 
 ### References
 

nifty4/library/wiener_filter_curvature.py

@@ -60,19 +60,6 @@ class WienerFilterCurvature(EndomorphicOperator):
         return self._op.apply(x, mode)
 
     def draw_sample(self):
-        """ Generates a sample from a Gaussian distribution with
-        covariance given by the operator.
-
-        This method generates samples by setting up the observation and
-        reconstruction of a mock signal in order to obtain residuals of the
-        right correlation.
-
-        Returns
-        -------
-        sample : Field
-            Returns the a sample from the Gaussian of given covariance.
-        """
-
         mock_signal = self.S.draw_sample()
         mock_noise = self.N.draw_sample()
 

nifty4/operators/diagonal_operator.py

@@ -142,19 +142,6 @@ class DiagonalOperator(EndomorphicOperator):
                                 self._spaces)
 
     def draw_sample(self):
-        """ Generates a sample from a Gaussian distribution with
-        covariance given by the operator.
-
-        This method generates samples by setting up the observation and
-        reconstruction of a mock signal in order to obtain residuals of the
-        right correlation.
-
-        Returns
-        -------
-        sample : Field
-            Returns the a sample from the Gaussian of given covariance.
-        """
-
         if self._spaces is not None:
             raise ValueError("Cannot draw (yet) from this operator")
 

nifty4/operators/linear_operator.py

@@ -162,3 +162,18 @@ class LinearOperator(with_metaclass(
         self._check_mode(mode)
         if x.domain != self._dom(mode):
             raise ValueError("The operator's and field's domains don't match.")
+
+    def draw_sample(self):
+        """ Generates a sample from a Gaussian distribution with
+        covariance given by the operator.
+
+        This method generates samples by setting up the observation and
+        reconstruction of a mock signal in order to obtain residuals of the
+        right correlation.
+
+        Returns
+        -------
+        sample : Field
+            Returns the a sample from the Gaussian of given covariance.
+        """
+        raise NotImplementedError

nifty4/operators/scaling_operator.py

@@ -90,19 +90,6 @@ class ScalingOperator(EndomorphicOperator):
                 self.INVERSE_TIMES | self.ADJOINT_INVERSE_TIMES)
 
     def draw_sample(self):
-        """ Generates a sample from a Gaussian distribution with
-        covariance given by the operator.
-
-        This method generates samples by setting up the observation and
-        reconstruction of a mock signal in order to obtain residuals of the
-        right correlation.
-
-        Returns
-        -------
-        sample : Field
-            Returns the a sample from the Gaussian of given covariance.
-        """
-
         return Field.from_random(random_type="normal",
                                  domain=self._domain,
                                  std=np.sqrt(self._factor),