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我有一个 C++ 多项式类的问题，我无法找到解决方案。

我试图以这种方式推导出一个有理函数：

z=dnum.derive();
cout<<"Derive Num: "<<z<<endl;
y=dden.derive();
cout<<"Derive Den: "<<y<<endl;
t=z*dden;
cout<<"NumAdd1: "<<t<<endl;
s=y*dnum;
cout<<"NumAdd2: "<<s<<endl;
dnum=t-s;
cout<<"New NUM: "<<dnum<<endl;
t=dden*dden;
dden=t;
cout<<"New DEN: "<<dden<<endl;

结果是这样的：

Original Num: 3.30688e-05 x^5 +0.000992063 x^4 +0.0138889 x^3 +0.111111 x^2 +0.5 x +1
Original Den: -3.30688e-05 x^5 +0.000992063 x^4 -0.0138889 x^3 +0.111111 x^2 -0.5 x +1

Derive Num: 0.000165344 x^4 +0.00396825 x^3 +0.0416667 x^2 +0.222222 x +0.5
Derive Den: -0.000165344 x^4 +0.00396825 x^3 -0.0416667 x^2 +0.222222 x -0.5

NumAdd1: -5.46772e-09 x^9 +3.28063e-08 x^8 +2.62451e-07 x^7 -2.75573e-06 x^6 -1.65344e-05 x^5 +0.000220459 x^4 +0.000881834 x^3 -0.0138889 x^2 -0.0277778 x +0.5
NumAdd2: -5.46772e-09 x^9 -3.28063e-08 x^8 +2.62451e-07 x^7 +2.75573e-06 x^6 -1.65344e-05 x^5 -0.000220459 x^4 +0.000881834 x^3 +0.0138889 x^2 -0.0277778 x -0.5

New NUM: 6.56127e-08 x^8 -8.13575e-19 x^7 -5.51146e-06 x^6 -2.7349e-17 x^5 +0.000440917 x^4 +4.996e-16 x^3 -0.0277778 x^2 -5.32907e-15 x +1

New DEN: 1.09354e-09 x^10 -6.56127e-08 x^9 +1.90277e-06 x^8 -3.49059e-05 x^7 +0.000446429 x^6 -0.00407848 x^5 +0.0262346 x^4 -0.111111 x^3 +0.25 x^2

导数的分子似乎是正确的，但分母不正确，因为没有次数低于 2 的单项式，例如，应该有“+1”。

我认为重载有问题operator*（但它适用于分子）

Polynomial Polynomial::operator*(const Polynomial fact)const {
    double *new_coeff;
    int degree;

    degree = deg + fact.deg;
    new_coeff= new double[degree+1];

    for(int i=0;i<=degree;i++) new_coeff[i]=0.0;

    for(int i=0;i<=deg;i++){
        for(int j=0;j<=fact.deg;j++){
            if((coeff[i]!=0) && (fact.coeff[j]!=0)){
                new_coeff[i+j] += coeff[i]*fact.coeff[j];
            }
        }
    }
    return Polynomial(degree,new_coeff);
}

或在重载operator=

Polynomial & Polynomial::operator= ( const Polynomial &poly )
{
    if ( this == &poly ) return ( *this );
    else{
        deg=poly.getdegree();
        coeff= new double[deg+1];

        for (int i=0; i <= deg; i++)
            coeff[i] = poly.coeff[i];
    }
    return ( *this );
}

你有什么建议吗？

ps如果我的问题有问题，请原谅我......这是我在这里的第一篇文章。

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