TermProduct.cc

/* 
 * File:   TermProduct.cc
 * 
 * Copyright 2012 Heinrich Schuchardt <xypron.glpk@gmx.de>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "Problem.h"
#include "TermConstant.h"
#include "TermProduct.h"
#include "TermSum.h"
#include "TermVariable.h"
#include <sstream>
#include <typeinfo>

TermProduct::TermProduct(Problem* problem,
        Term* factor1, Term* factor2) :
TermBinary::TermBinary(problem) {
    if (factor1->less(factor2)) {
        this->factor1_ = factor1;
        this->factor2_ = factor2;
    } else {
        this->factor1_ = factor2;
        this->factor2_ = factor1;
    }
}

TermProduct::~TermProduct() {
}

Term* TermProduct::create(Problem* problem,
        Term* factor1, Term* factor2) {
    double value1;

    if (typeid (*factor1) == typeid (TermConstant)) {
        value1 = (static_cast<TermConstant *> (factor1))->evaluate();
        if (value1 == 0.) {
            return factor1;
        }
        if (value1 == 1.) {
            return factor2;
        }
    }
    if (typeid (*factor2) == typeid (TermConstant)) {
        double value2;
        value2 = (static_cast<TermConstant *> (factor2))->evaluate();
        if (value2 == 0.) {
            return factor2;
        }
        if (value2 == 1.) {
            return factor1;
        }
        if (typeid (*factor1) == typeid (TermConstant)) {
            return TermConstant::create(problem,
                    value1 * value2);
        }
    }

    TermProduct* term = new TermProduct(problem, factor1, factor2);
    term = static_cast<TermProduct*> (problem->addTerm(term));
    return term;
}

Term* TermProduct::differentiate(TermVariable* variable) throw
(ProblemMismatchException) {
    Problem* problem = this->getProblem();
    if (problem != variable->getProblem()) {
        ProblemMismatchException problem_mismatch_exception;
        throw problem_mismatch_exception;
    }
    return TermSum::create(problem,
            TermProduct::create(problem,
            this->factor1_->differentiate(variable),
            this->factor2_),
            TermProduct::create(problem,
            this->factor1_,
            this->factor2_->differentiate(variable)));

}

double TermProduct::eval(const DoubleVector* variableValues,
        TermValueSet* termValues) {
    return this->factor1_->evaluate(variableValues, termValues) *
            this->factor2_->evaluate(variableValues, termValues);
}

bool TermProduct::less(const Term* term) const {
    const TermProduct* term_product;
    if (this->Term::less(term)) {
        return true;
    } else if (term->Term::less(this)) {
        return false;
    }
    term_product = static_cast<const TermProduct *> (term);
    if (this->factor1_ < term_product->factor1_) {
        return true;
    } else if (term_product->factor1_ < this->factor1_) {
        return false;
    }
    if (this->factor2_ < term_product->factor2_) {
        return true;
    } else {
        return false;
    }
}

std::string TermProduct::toString() const {
    std::ostringstream os;
    os << "(" << this->factor1_ << " * " << this->factor2_ << ")";
    return os.str();
}