typedef double[] (*fp) (double a[], int n);

fp* fkt = new fp[3];

fkt[0] = f1;
fkt[1] = f2;
fkt[2] = f3;

//Aufruf:
ptrd = newton(fkt,3,&error);

double* newton(fp fkts[], int anzahl, int *error)
   {
      double * rs = new double[anzahl];
      error = new int[anzahl];

   for (int i=0; i<anzahl, i++)
         {...}

return rs;
}