protected DecimalTypeInfo deriveResultDecimalTypeInfo() {
    int prec1 = leftOI.precision();
    int prec2 = rightOI.precision();
    int scale1 = leftOI.scale();
    int scale2 = rightOI.scale();
    return deriveResultDecimalTypeInfo(prec1, scale1, prec2, scale2);
  }
Derive the object inspector instance for the decimal result of the operator.
ql/src/java/org/apache/hadoop/hive/ql/udf/generic/GenericUDFBaseNumeric.java