line_search.py 1.72 KB
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# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
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#
# Copyright(C) 2013-2017 Max-Planck-Society
#
# NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
# and financially supported by the Studienstiftung des deutschen Volkes.
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import abc

from keepers import Loggable

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from ...energies import LineEnergy
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from future.utils import with_metaclass
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class LineSearch(with_metaclass(abc.ABCMeta, type('NewBase', (Loggable, object), {}))):
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    """Class for determining the optimal step size along some descent direction.
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    Initialize the line search procedure which can be used by a specific line
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    search method. It finds the step size in a specific direction in the
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    minimization process.
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    Attributes
    ----------
    line_energy : LineEnergy Object
        LineEnergy object from which we can extract energy at a specific point.
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    preferred_initial_step_size : float
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        Initial guess for the step length.
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    """

    __metaclass__ = abc.ABCMeta

    def __init__(self):
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        self.preferred_initial_step_size = None
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    @abc.abstractmethod
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    def perform_line_search(self, energy, pk, f_k_minus_1=None):
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        raise NotImplementedError