protected void cleanup(DoubleColumnVector outputColVector, int[] sel,
      boolean selectedInUse, int n) {
    MathExpr.NaNToNull(outputColVector, sel, selectedInUse, n);
  }
Implement vectorized math function that takes a double (and optionally additional
constant argument(s)) and returns long.
May be used for functions like ROUND(d, N), Pow(a, p) etc.

Do NOT use this for simple math functions like sin/cos/exp etc. that just take
a single argument. For those, modify the template ColumnUnaryFunc.txt
and expand the template to generate needed classes.
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/expressions/MathFuncLongToDouble.java