Commit 0b086b5f authored by Torsten Ensslin's avatar Torsten Ensslin
Browse files

started with documentation of energy_operators

parent 88c03baa
...@@ -27,10 +27,31 @@ from .simple_linear_operators import VdotOperator ...@@ -27,10 +27,31 @@ from .simple_linear_operators import VdotOperator
class EnergyOperator(Operator): class EnergyOperator(Operator):
""" NIFTy class for Energy operators.
The NIFTy EnergyOperator class derives from the Operator class.
An EnergyOperators transforms a field into a scalar, the information energy
of the field. Typically, an EnergyOperators is an information Hamiltonian
( = negative log probability) or a Gibbs free energy ( = averaged
Hamiltonian), aka Kullbach-Leibler divergence.
An EnergyOperator can also provide its gradient as an EndomorphicOperator
that converts a field into a field, the gradient of the Hamiltonian at the
field location.
# TE FIXME: find out and document how gradient and metric are invoked
_target = DomainTuple.scalar_domain() _target = DomainTuple.scalar_domain()
class SquaredNormOperator(EnergyOperator): class SquaredNormOperator(EnergyOperator):
""" NIFTy class for a squared norm energy.
The NIFTy SquaredNormOperator class derives from the EnergyOperator class.
A SquaredNormOperator represents a field energy E that is the L2 norm of a
field f: E = f^dagger f
def __init__(self, domain): def __init__(self, domain):
self._domain = domain self._domain = domain
...@@ -44,6 +65,13 @@ class SquaredNormOperator(EnergyOperator): ...@@ -44,6 +65,13 @@ class SquaredNormOperator(EnergyOperator):
class QuadraticFormOperator(EnergyOperator): class QuadraticFormOperator(EnergyOperator):
""" NIFTy class for quadratic field energies.
The NIFTy QuadraticFormOperator derives from the EnergyOperator class.
It represents a field energy E that is a quadratic form of a field f with
kernel op: E = f^dagger op f /2
def __init__(self, op): def __init__(self, op):
from .endomorphic_operator import EndomorphicOperator from .endomorphic_operator import EndomorphicOperator
if not isinstance(op, EndomorphicOperator): if not isinstance(op, EndomorphicOperator):
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