示例#1
0
    // given f and its derivative f_, and a init x0, return its newton_iteration result to find a root
    static bool newton_root(long double x0, const Polynomial & f, const Polynomial & f_, long double & root)
    {
        root = x0;
        long double nf, nf_;
        int iter = 0;
        while (fabs(nf = f.func(root)) > smalleps)
        {
            nf_ = f_.func(root);
            if (fabs(nf_) < smalleps) return false;
            root = root - nf / nf_;

            iter++;
            if (iter >= 128) return false;
        }
        return true;
    }
示例#2
0
 // after we find a root of a polynomial, use this method to determine its multiple
 static int findRootMultiple(long double x, const Polynomial & f)
 {
     int ret = 1;
     Polynomial now = f;
     double zeroeps = 1e-6;
     while (true)
     {
         now = now.qiudiao();
         if (now.coff.size() == 0) break;
         long double nowf = now.func(x);
         if (fabs(nowf) < zeroeps) ret++;
         else 	break;
         zeroeps *= 4;
     }
     return ret;
 }