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#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Created on Fri Mar 8 09:55:36 2019
@author: evangelos
"""
from ccpi.optimisation.functions import Function
from ccpi.optimisation.functions import ScaledFunction
class FunctionOperatorComposition(Function):
''' Function composition with Operator, i.e., f(Ax)
A: operator
f: function
'''
def __init__(self, operator, function):
super(FunctionOperatorComposition, self).__init__()
self.function = function
self.operator = operator
alpha = 1
if isinstance (function, ScaledFunction):
alpha = function.scalar
self.L = 2 * alpha * operator.norm()**2
def __call__(self, x):
''' Evaluate FunctionOperatorComposition at x
returns f(Ax)
'''
return self.function(self.operator.direct(x))
#TODO do not know if we need it
def call_adjoint(self, x):
return self.function(self.operator.adjoint(x))
def convex_conjugate(self, x):
''' convex_conjugate does not take into account the Operator'''
return self.function.convex_conjugate(x)
def proximal(self, x, tau, out=None):
'''proximal does not take into account the Operator'''
if out is None:
return self.function.proximal(x, tau)
else:
self.function.proximal(x, tau, out=out)
def proximal_conjugate(self, x, tau, out=None):
''' proximal conjugate does not take into account the Operator'''
if out is None:
return self.function.proximal_conjugate(x, tau)
else:
self.function.proximal_conjugate(x, tau, out=out)
def gradient(self, x, out=None):
''' Gradient takes into account the Operator'''
if out is None:
return self.operator.adjoint(
self.function.gradient(self.operator.direct(x))
)
else:
self.operator.adjoint(
self.function.gradient(self.operator.direct(x),
out=out)
)
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