Factorization.h

Go to the documentation of this file.

#pragma once
 
#include "Power.h"
 
#include <carl-logging/carl-logging.h>
#include "../CoCoAAdaptor.h"
#include <carl-arith/converter/OldGinacConverter.h>
#include <carl-arith/core/Common.h>
 
namespace carl {
 
template<typename C, typename O, typename P>
class MultivariatePolynomial;
 
namespace helper {
    /**
     * Returns a factors datastructure containing only the full polynomial as single factor.
     */
    template<typename C, typename O, typename P>
    Factors<MultivariatePolynomial<C,O,P>> trivialFactorization(const MultivariatePolynomial<C,O,P>& p) {
        return { std::make_pair(p, 1) };
    }
 
} // namespace helper
 
/**
 * Try to factorize a multivariate polynomial..
 * Uses CoCoALib and GiNaC, if available, depending on the coefficient type of the polynomial.
 */
template<typename C, typename O, typename P>
Factors<MultivariatePolynomial<C,O,P>> factorization(const MultivariatePolynomial<C,O,P>& p, bool includeConstants = true) {
    if (p.total_degree() == 0) {
        if (includeConstants) {
            return helper::trivialFactorization(p);
        } else {
            return {};
        }
    } else if (p.total_degree() == 1) {
        return helper::trivialFactorization(p);
    }
 
    auto s = overloaded {
    #if defined USE_COCOA
        [includeConstants](const MultivariatePolynomial<mpq_class,O,P>& p){ CoCoAAdaptor<MultivariatePolynomial<mpq_class,O,P>> c({p}); return c.factorize(p, includeConstants); },
        [includeConstants](const MultivariatePolynomial<mpz_class,O,P>& p){ CoCoAAdaptor<MultivariatePolynomial<mpz_class,O,P>> c({p}); return c.factorize(p, includeConstants); }
    #else
        [](const MultivariatePolynomial<mpq_class,O,P>& p){ return helper::trivialFactorization(p); },
        [](const MultivariatePolynomial<mpz_class,O,P>& p){ return helper::trivialFactorization(p); }
    #endif
    #if defined USE_GINAC
        ,
        [](const MultivariatePolynomial<cln::cl_RA,O,P>& p){ return ginacFactorization(p); },
        [](const MultivariatePolynomial<cln::cl_I,O,P>& p){ return ginacFactorization(p); }
    #endif
    };
 
    auto factors = s(p);
    return factors;
}
 
template<typename C, typename O, typename P>
bool is_trivial(const Factors<MultivariatePolynomial<C,O,P>>& f) {
    return f.size() <= 1;
}
 
 
/**
 * Try to factorize a multivariate polynomial and return the irreducible factors (without multiplicities).
 * Uses CoCoALib and GiNaC, if available, depending on the coefficient type of the polynomial.
 */
template<typename C, typename O, typename P>
std::vector<MultivariatePolynomial<C,O,P>> irreducible_factors(const MultivariatePolynomial<C,O,P>& p, bool includeConstants = true) {
    if (p.total_degree() == 0) {
        if (includeConstants) {
            return {p};
        } else {
            return {};
        }
    } else if (p.total_degree() == 1) {
        return {p};
    }
 
    auto s = overloaded {
    #if defined USE_COCOA
        [includeConstants](const MultivariatePolynomial<mpq_class,O,P>& p){ CoCoAAdaptor<MultivariatePolynomial<mpq_class,O,P>> c({p}); return c.irreducible_factors(p, includeConstants); },
        [includeConstants](const MultivariatePolynomial<mpz_class,O,P>& p){ CoCoAAdaptor<MultivariatePolynomial<mpz_class,O,P>> c({p}); return c.irreducible_factors(p, includeConstants); }
    #else
        [includeConstants](const MultivariatePolynomial<mpq_class,O,P>& p){ return std::vector<MultivariatePolynomial<mpq_class,O,P>>({p}); },
        [includeConstants](const MultivariatePolynomial<mpz_class,O,P>& p){ return std::vector<MultivariatePolynomial<mpz_class,O,P>>({p}); }
    #endif
    #if defined USE_GINAC
        ,
        [](const MultivariatePolynomial<cln::cl_RA,O,P>& p){ return std::vector<MultivariatePolynomial<cln::cl_RA,O,P>>({p}); },
        [](const MultivariatePolynomial<cln::cl_I,O,P>& p){ return std::vector<MultivariatePolynomial<cln::cl_I,O,P>>({p}); }
    #endif
    };
    return s(p);
}
 
}