# 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 .
#
# 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 ..field import Field, exp, tanh
class Linear(object):
def __call__(self, x):
return x
def derivative(self, x):
return Field.ones_like(x)
class Exponential(object):
def __call__(self, x):
return exp(x)
def derivative(self, x):
return exp(x)
class Tanh(object):
def __call__(self, x):
return tanh(x)
def derivative(self, x):
return (1. - tanh(x)**2)
class PositiveTanh(object):
def __call__(self, x):
return 0.5 * tanh(x) + 0.5
def derivative(self, x):
return 0.5 * (1. - tanh(x)**2)