GCD.h

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#pragma once
 
#include "../MultivariatePolynomial.h"
#include "../UnivariatePolynomial.h"
#include <carl-arith/numbers/typetraits.h>
#include "VarInfo.h"
 
namespace carl {
    template<typename C, typename O, typename P>
    MultivariatePolynomial<C,O,P> gcd(const MultivariatePolynomial<C,O,P>& a, const MultivariatePolynomial<C,O,P>& b);
    
    template<typename Coeff>
    UnivariatePolynomial<Coeff> gcd(const UnivariatePolynomial<Coeff>& a, const UnivariatePolynomial<Coeff>& b);
}
 
#include "GCD_multivariate.h"
#include "GCD_univariate.h"
#include "PrimitiveEuclidean.h"
 
namespace carl {
 
template<typename C, typename O, typename P>
Term<C> gcd(const MultivariatePolynomial<C,O,P>& a, const Term<C>& b) {
    static_assert(is_field_type<C>::value, "Only implemented for field coefficients");
    assert(!is_zero(a));
    assert(!is_zero(b));
    if (b.is_constant()) return Term<C>(C(1));
    return Term<C>(C(1), gcd(a, b.monomial()));
}
 
template<typename C, typename O, typename P>
Term<C> gcd(const Term<C>& a, const MultivariatePolynomial<C,O,P>& b) {
    return gcd(b, a);
}
 
template<typename C, typename O, typename P>
Monomial::Arg gcd(const MultivariatePolynomial<C,O,P>& a, const Monomial::Arg& b) {
    if (!b) return nullptr;
    assert(!is_zero(a));
    auto varinfo = carl::vars_info(a,false);
    std::vector<std::pair<Variable, exponent>> vepairs;
    for (const auto& ve : *b) {
        if (varinfo.var(ve.first)->num_occurences() == a.nr_terms()) {
            vepairs.push_back(ve.first, std::min(varinfo.var(ve.first)->min_degree(), ve.second));
        }
    }
    return createMonomial(std::move(vepairs));
}
 
template<typename C, typename O, typename P>
Monomial::Arg gcd(const Monomial::Arg& a, const MultivariatePolynomial<C,O,P>& b) {
    return gcd(b, a);
}
 
}