newthonRootMethod.cpp

float f (float V)
{
    float fx1;
    fx1 = (p + a*pow((N/V), 2))*(V - N*b) - k*N*T;
    return (fx1);
}

float df (float V)
{
    float fx1;
    fx1 = -2*a*pow(N, 2)*(V - b*N)/pow(V, 3) + (a*pow(N, 2)/pow(V, 2)) - k*T + p;
    return (fx1);
}


int main()
{
    int itr, maxmitr;
    float h, x0, x1, allerr;
    x0 = 1;
    allerr = tolerance;
    maxmitr = 45;
    
    for (itr=1; itr<=maxmitr; itr++)
    {
        h=f(x0)/df(x0);
        x1=x0-h;
        printf("root = %f \n", itr, x1);
        if (fabs(h) < allerr)
        {
            printf("root = %f \n", itr, x1);
            return 0;
        }
        x0=x1;
    }
    return 1;
}