static int absDoubleMaxIndex(double[] l, int from, int to) {
  double max = -Double.MAX_VALUE;
  int idx = -1;
  for (int i = from; i < to; i++) {
    double d = abs(l[i]);
    if (d > max) {
      max = d;
      idx = i;
    }
  }
  ret idx;
}