smoothness_operator.py 2.13 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
# 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/>.
#
# Copyright(C) 2013-2018 Max-Planck-Society
#
# NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
# and financially supported by the Studienstiftung des deutschen Volkes.

Martin Reinecke's avatar
Martin Reinecke committed
19
from .scaling_operator import ScalingOperator
Martin Reinecke's avatar
Martin Reinecke committed
20
from .laplace_operator import LaplaceOperator
21 22


Martin Reinecke's avatar
Martin Reinecke committed
23
def SmoothnessOperator(domain, strength=1., logarithmic=True, space=None):
24 25
    """An operator measuring the smoothness on an irregular grid with respect
    to some scale.
Jakob Knollmueller's avatar
Jakob Knollmueller committed
26

27 28 29 30 31 32 33 34
    This operator applies the irregular LaplaceOperator and its adjoint to some
    Field over a PowerSpace which corresponds to its smoothness and weights the
    result with a scale parameter sigma. It is used in the smoothness prior
    terms of the CriticalPowerEnergy. For this purpose we use free boundary
    conditions in the LaplaceOperator, having no curvature at both ends. In
    addition the first entry is ignored as well, corresponding to the overall
    mean of the map. The mean is therefore not considered in the smoothness
    prior.
Jakob Knollmueller's avatar
Jakob Knollmueller committed
35 36 37 38


    Parameters
    ----------
Martin Reinecke's avatar
Martin Reinecke committed
39
    strength: nonnegative float
Jakob Knollmueller's avatar
Jakob Knollmueller committed
40
        Specifies the strength of the SmoothnessOperator
Martin Reinecke's avatar
Martin Reinecke committed
41
    logarithmic : boolean
Jakob Knollmueller's avatar
Jakob Knollmueller committed
42 43 44
        Whether smoothness is calculated on a logarithmic scale or linear scale
        default : True
    """
Martin Reinecke's avatar
Martin Reinecke committed
45 46 47 48 49 50
    if strength < 0:
        raise ValueError("ERROR: strength must be nonnegative.")
    if strength == 0.:
        return ScalingOperator(0., domain)
    laplace = LaplaceOperator(domain, logarithmic=logarithmic, space=space)
    return (strength**2)*laplace.adjoint*laplace