return 1.0/Double.valueOf(frombase).doubleValue();
return "(1.0/"+frombase+")";
    double computeToFactor(String context, String unit) {      String base = getBaseUnit(context);      if (base.equals(unit)) return 1.0;      String tobase = p.get(context, "to_"+unit);      if (tobase != null) {        return Double.valueOf(tobase).doubleValue();      } else {        String frombase = p.get(context, "from_"+unit);        if (frombase == null) {          // no info here!  Try what we extend:          return computeToFactor(p.get(context,"extends"), unit);        }        return 1.0/Double.valueOf(frombase).doubleValue();      }    }