OffsetOperator -> Adder

nifty5/__init__.py

@@ -19,6 +19,7 @@ from .field import Field
 from .multi_field import MultiField
 
 from .operators.operator import Operator
+from .operators.adder import Adder
 from .operators.diagonal_operator import DiagonalOperator
 from .operators.distributors import DOFDistributor, PowerDistributor
 from .operators.domain_tuple_field_inserter import DomainTupleFieldInserter
@@ -33,7 +34,6 @@ from .operators.field_zero_padder import FieldZeroPadder
 from .operators.inversion_enabler import InversionEnabler
 from .operators.linear_operator import LinearOperator
 from .operators.mask_operator import MaskOperator
-from .operators.offset_operator import OffsetOperator
 from .operators.qht_operator import QHTOperator
 from .operators.regridding_operator import RegriddingOperator
 from .operators.sampling_enabler import SamplingEnabler

nifty5/library/smooth_linear_amplitude.py

@@ -20,8 +20,8 @@ import numpy as np
 from ..domain_tuple import DomainTuple
 from ..domains.power_space import PowerSpace
 from ..field import Field
+from ..operators.adder import Adder
 from ..operators.exp_transform import ExpTransform
-from ..operators.offset_operator import OffsetOperator
 from ..operators.qht_operator import QHTOperator
 from ..operators.slope_operator import SlopeOperator
 from ..operators.symmetrizing_operator import SymmetrizingOperator
@@ -29,7 +29,7 @@ from ..sugar import makeOp
 
 
 def _ceps_kernel(k, a, k0):
-    return (a/(1+np.sum((k.T/k0)**2, axis=-1).T))**2
+    return (a/(1 + np.sum((k.T/k0)**2, axis=-1).T))**2
 
 
 def CepstrumOperator(target, a, k0):
@@ -189,7 +189,7 @@ def SLAmplitude(*, target, n_pix, a, k0, sm, sv, im, iv, keys=['tau', 'phi']):
     sig = np.array([sv, iv])
     mean = Field.from_global_data(sl.domain, mean)
     sig = Field.from_global_data(sl.domain, sig)
-    linear = (sl @ OffsetOperator(mean) @ makeOp(sig)).ducktape(keys[1])
+    linear = sl @ Adder(mean) @ makeOp(sig).ducktape(keys[1])
 
     # Combine linear and smooth component
     loglog_ampl = 0.5*(smooth + linear)

nifty5/operators/offset_operator.py → nifty5/operators/adder.py

@@ -15,18 +15,22 @@
 #
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik.
 
+from ..field import Field
+from ..multi_field import MultiField
 from .operator import Operator
 
 
-class OffsetOperator(Operator):
-    """Shifts the input by a fixed field.
+class Adder(Operator):
+    """Adds a fixed field.
 
     Parameters
     ----------
-    field : Field
+    field : Field or MultiField
         The field by which the input is shifted.
     """
     def __init__(self, field):
+        if not isinstance(field, (Field, MultiField)):
+            raise TypeError
         self._field = field
         self._domain = self._target = field.domain