# Source code for nifty7.operators.outer_product_operator

# 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) 2013-2020 Max-Planck-Society
#
# NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik.
import numpy as np
from ..domain_tuple import DomainTuple
from ..field import Field
from .linear_operator import LinearOperator
[docs]class OuterProduct(LinearOperator):
"""Performs the point-wise outer product of two fields.
Parameters
---------
domain: DomainTuple, the domain of the input field
field: Field
---------
"""
def __init__(self, domain, field):
self._domain = DomainTuple.make(domain)
self._field = field
self._target = DomainTuple.make(
tuple(sub_d for sub_d in field.domain._dom + self._domain._dom))
self._capability = self.TIMES | self.ADJOINT_TIMES
[docs] def apply(self, x, mode):
self._check_input(x, mode)
if mode == self.TIMES:
return Field(
self._target, np.multiply.outer(
self._field.val, x.val))
axes = len(self._field.shape)
return Field(
self._domain, np.tensordot(self._field.val, x.val, axes))