Source code for nifty7.operators.inversion_enabler

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# Copyright(C) 2013-2020 Max-Planck-Society
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# NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik.

from ..logger import logger
from ..minimization.conjugate_gradient import ConjugateGradient
from ..minimization.iteration_controllers import IterationController
from ..minimization.quadratic_energy import QuadraticEnergy
from ..sugar import full
from .endomorphic_operator import EndomorphicOperator
from .linear_operator import LinearOperator


[docs]class InversionEnabler(EndomorphicOperator): """Class which augments the capability of another operator object via numerical inversion. Parameters ---------- op : :class:`EndomorphicOperator` The operator to be enhanced. The InversionEnabler object will support the same operation modes as `op`, and additionally the inverse set. The newly-added modes will be computed by iterative inversion. iteration_controller : :class:`IterationController` The iteration controller to use for the iterative numerical inversion done by a :class:`ConjugateGradient` object. approximation : :class:`LinearOperator`, optional if not None, this operator should be an approximation to `op`, which supports the operation modes that `op` doesn't have. It is used as a preconditioner during the iterative inversion, to accelerate convergence. """ def __init__(self, op, iteration_controller, approximation=None): # isinstance(op, EndomorphicOperator) does not suffice since op can be # a ChainOperator if not isinstance(op, LinearOperator): raise TypeError('Operator needs to be linear.') if op.domain is not op.target: raise TypeError('Operator needs to be endomorphic.') self._op = op self._ic = iteration_controller self._approximation = approximation self._domain = op.domain self._capability = self._addInverse[self._op.capability]
[docs] def apply(self, x, mode): self._check_mode(mode) if self._op.capability & mode: return self._op.apply(x, mode) x0 = full(x.domain, 0.) invmode = self._modeTable[self.INVERSE_BIT][self._ilog[mode]] invop = self._op._flip_modes(self._ilog[invmode]) prec = self._approximation if prec is not None: prec = prec._flip_modes(self._ilog[mode]) energy = QuadraticEnergy(x0, invop, x) inverter = ConjugateGradient(self._ic) r, stat = inverter(energy, preconditioner=prec) if stat != IterationController.CONVERGED: logger.warning("Error detected during operator inversion") return r.position
[docs] def draw_sample(self, from_inverse=False): return self._op.draw_sample(from_inverse)
[docs] def draw_sample_with_dtype(self, dtype, from_inverse=False): return self._op.draw_sample_with_dtype(dtype, from_inverse)