SCIP in C++11 ― 2.2.3節 その2

Hornerの方法：問題2.34

問題2.33のlengthにとても良く似ている問題と気づけば簡単。

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typedef double CoefficientRing;

// Horner's method

const CoefficientRing evaluateHorner

(const CoefficientRing& x, const List& polynomial)

{

    function<CoefficientRing(CoefficientRing,CoefficientRing)>

        riseHorner=[x]

        (const CoefficientRing& a_i,const CoefficientRing& higherTerms)

        {return(a_i+x*higherTerms);};

    const CoefficientRing zero(0);

    return(accumulate(riseHorner,zero,polynomial));

}

int main(int argc, char** argv)

{

    typedef double Coefficient;

    const auto polynomialCoefficients

        (makeList(1.0,3.0,0.0,5.0,0.0,1.0));

    cout<<"1+3x+5x^3+x^5 (x=2) = "

        <<evaluateHorner(2.0,polynomialCoefficients)<<endl;

    return(0);

}

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出力

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1+3x+5x^3+x^5 (x=2) = 79