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/*
Author: Juan Rada-Vilela, Ph.D.
Copyright (C) 2010-2014 FuzzyLite Limited
All rights reserved
This file is part of fuzzylite.
fuzzylite is free software: you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the Free
Software Foundation, either version 3 of the License, or (at your option)
any later version.
fuzzylite 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 Lesser General Public License
for more details.
You should have received a copy of the GNU Lesser General Public License
along with fuzzylite. If not, see <http://www.gnu.org/licenses/>.
fuzzylite™ is a trademark of FuzzyLite Limited.
*/
#include "fl/term/Sigmoid.h"
namespace fl {
Sigmoid::Sigmoid(const std::string& name, scalar inflection, scalar slope, scalar height)
: Term(name, height), _inflection(inflection), _slope(slope) {
}
Sigmoid::~Sigmoid() {
}
std::string Sigmoid::className() const {
return "Sigmoid";
}
scalar Sigmoid::membership(scalar x) const {
if (fl::Op::isNaN(x)) return fl::nan;
return _height * 1.0 / (1.0 + std::exp(-_slope * (x - _inflection)));
}
std::string Sigmoid::parameters() const {
return Op::join(2, " ", _inflection, _slope) +
(not Op::isEq(_height, 1.0) ? " " + Op::str(_height) : "");
}
void Sigmoid::configure(const std::string& parameters) {
if (parameters.empty()) return;
std::vector<std::string> values = Op::split(parameters, " ");
std::size_t required = 2;
if (values.size() < required) {
std::ostringstream ex;
ex << "[configuration error] term <" << className() << ">"
<< " requires <" << required << "> parameters";
throw fl::Exception(ex.str(), FL_AT);
}
setInflection(Op::toScalar(values.at(0)));
setSlope(Op::toScalar(values.at(1)));
if (values.size() > required)
setHeight(Op::toScalar(values.at(required)));
}
void Sigmoid::setSlope(scalar a) {
this->_slope = a;
}
scalar Sigmoid::getSlope() const {
return this->_slope;
}
void Sigmoid::setInflection(scalar c) {
this->_inflection = c;
}
scalar Sigmoid::getInflection() const {
return this->_inflection;
}
Sigmoid::Direction Sigmoid::direction() const {
if (not fl::Op::isFinite(_slope) or fl::Op::isEq(_slope, 0.0)) return ZERO;
if (fl::Op::isGt(_slope, 0.0)) return POSITIVE;
return NEGATIVE;
}
Sigmoid* Sigmoid::clone() const {
return new Sigmoid(*this);
}
Term* Sigmoid::constructor() {
return new Sigmoid;
}
}
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