@Override
  protected Double divide(Long number, long divisor) {
    return VectorPTFEvaluatorHelper.divide(number, divisor);
  }
This class evaluates long avg() for a PTF group.

Sum up non-null column values; group result is sum / non-null count.
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/ptf/VectorPTFEvaluatorLongAvg.java