null_operator.py 2.03 KB
Newer Older
Martin Reinecke's avatar
Martin Reinecke committed
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
# 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.

from __future__ import absolute_import, division, print_function
from ..compat import *
from ..domain_tuple import DomainTuple
from ..field import Field
Martin Reinecke's avatar
Martin Reinecke committed
23
from ..multi_field import MultiField
Martin Reinecke's avatar
Martin Reinecke committed
24
25
26
27
28
29
30
31
32
33
34
35
36
from ..operators.linear_operator import LinearOperator


class NullOperator(LinearOperator):
    """Operator corresponding to a matrix of all zeros.

    Parameters
    ----------
    domain : DomainTuple or MultiDomain
        input domain
    target : DomainTuple or MultiDomain
        output domain
    """
Philipp Arras's avatar
Philipp Arras committed
37

Martin Reinecke's avatar
Martin Reinecke committed
38
39
40
41
42
43
44
    def __init__(self, domain, target):
        from ..sugar import makeDomain
        self._domain = makeDomain(domain)
        self._target = makeDomain(target)

    @staticmethod
    def _nullfield(dom):
Martin Reinecke's avatar
Martin Reinecke committed
45
        if isinstance(dom, DomainTuple):
Martin Reinecke's avatar
fix    
Martin Reinecke committed
46
            return Field.full(dom, 0)
Martin Reinecke's avatar
Martin Reinecke committed
47
        else:
Martin Reinecke's avatar
fixes    
Martin Reinecke committed
48
            return MultiField.full(dom, 0)
Martin Reinecke's avatar
Martin Reinecke committed
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67

    def apply(self, x, mode):
        self._check_input(x, mode)

        if mode == self.TIMES:
            return self._nullfield(self._target)
        return self._nullfield(self._domain)

    @property
    def domain(self):
        return self._domain

    @property
    def target(self):
        return self._target

    @property
    def capability(self):
        return self.TIMES | self.ADJOINT_TIMES