# Source code for nifty7.operators.normal_operators

```# 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 ..domains.unstructured_domain import UnstructuredDomain
from ..operators.diagonal_operator import DiagonalOperator
from ..operators.simple_linear_operators import ducktape
from ..sugar import makeField
from ..utilities import lognormal_moments, value_reshaper

[docs]def NormalTransform(mean, sigma, key, N_copies=0):
"""Opchain that transforms standard normally distributed values to
normally distributed values with given mean and standard deviation.

Parameters
----------
mean : float
Mean of the field
sigma : float
Standard deviation of the field
key : string
Name of the operators domain (Multidomain)
N_copies : integer
If == 0, target will be a scalar field.
If >= 1, target will be an
:class:`~nifty7.domains.unstructured_domain.UnstructuredDomain`.
"""
if N_copies == 0:
domain = DomainTuple.scalar_domain()
mean, sigma = np.asfarray(mean), np.asfarray(sigma)
return mean_adder @ (sigma * ducktape(domain, None, key))

domain = UnstructuredDomain(N_copies)
mean, sigma = (value_reshaper(param, N_copies) for param in (mean, sigma))
sigma_op = DiagonalOperator(makeField(domain, sigma))
return mean_adder @ sigma_op @ ducktape(domain, None, key)

[docs]def LognormalTransform(mean, sigma, key, N_copies):
"""Opchain that transforms standard normally distributed values to
log-normally distributed values with given mean and standard deviation.

Parameters
----------
mean : float
Mean of the field
sigma : float
Standard deviation of the field
key : string
Name of the domain
N_copies : integer
If == 0, target will be a scalar field.
If >= 1, target will be an
:class:`~nifty7.domains.unstructured_domain.UnstructuredDomain`.
"""
logmean, logsigma = lognormal_moments(mean, sigma, N_copies)
return NormalTransform(logmean, logsigma, key, N_copies).ptw("exp")
```