static <A> ArrayList<Double> floatArrayToDoubleList(float[] a) {
  if (a == null) null;
  ret floatArrayToDoubleList(a, 0, a.length);
}

// no range checking on from/to in the interest of speed
static <A> ArrayList<Double> floatArrayToDoubleList(float[] a, int from, int to) {
  if (a == null) null;
  ArrayList<Double> l = new(to-from);
  for (int i = from; i < to; i++) l.add((double) a[i]);
  ret l;
}

Began life as a copy of #1036160