@Test
  public void testMathFunctions() throws HiveException {
    ExprNodeGenericFuncDesc mathFuncExpr = new ExprNodeGenericFuncDesc();
    mathFuncExpr.setTypeInfo(TypeInfoFactory.doubleTypeInfo);
    ExprNodeColumnDesc colDesc1 = new ExprNodeColumnDesc(Integer.class, "a", "table", false);
    ExprNodeColumnDesc colDesc2 = new ExprNodeColumnDesc(Double.class, "b", "table", false);
    List<ExprNodeDesc> children1 = new ArrayList<ExprNodeDesc>();
    List<ExprNodeDesc> children2 = new ArrayList<ExprNodeDesc>();
    children1.add(colDesc1);
    children2.add(colDesc2);

    List<String> columns = new ArrayList<String>();
    columns.add("b");
    columns.add("a");
    VectorizationContext vc = new VectorizationContext("name", columns);

    // Sin(double)
    GenericUDFBridge gudfBridge = new GenericUDFBridge("sin", false, UDFSin.class.getName());
    mathFuncExpr.setGenericUDF(gudfBridge);
    mathFuncExpr.setChildren(children2);
    VectorExpression ve = vc.getVectorExpression(mathFuncExpr, VectorExpressionDescriptor.Mode.PROJECTION);
    Assert.assertEquals(FuncSinDoubleToDouble.class, ve.getClass());

    // Round without digits
    GenericUDFRound udfRound = new GenericUDFRound();
    mathFuncExpr.setGenericUDF(udfRound);
    mathFuncExpr.setChildren(children2);
    ve = vc.getVectorExpression(mathFuncExpr);
    Assert.assertEquals(FuncRoundDoubleToDouble.class, ve.getClass());

    // BRound without digits
    GenericUDFBRound udfBRound = new GenericUDFBRound();
    mathFuncExpr.setGenericUDF(udfBRound);
    ve = vc.getVectorExpression(mathFuncExpr);
    Assert.assertEquals(FuncBRoundDoubleToDouble.class, ve.getClass());

    // Round with digits
    mathFuncExpr.setGenericUDF(udfRound);
    children2.add(new ExprNodeConstantDesc(4));
    mathFuncExpr.setChildren(children2);
    ve = vc.getVectorExpression(mathFuncExpr);
    Assert.assertEquals(RoundWithNumDigitsDoubleToDouble.class, ve.getClass());
    Assert.assertEquals(4, ((RoundWithNumDigitsDoubleToDouble) ve).getDecimalPlaces().get());

    // BRound with digits
    mathFuncExpr.setGenericUDF(udfBRound);
    ve = vc.getVectorExpression(mathFuncExpr);
    Assert.assertEquals(BRoundWithNumDigitsDoubleToDouble.class, ve.getClass());
    Assert.assertEquals(4, ((BRoundWithNumDigitsDoubleToDouble) ve).getDecimalPlaces().get());

    // Logger with int base
    gudfBridge = new GenericUDFBridge("log", false, UDFLog.class.getName());
    mathFuncExpr.setGenericUDF(gudfBridge);
    children2.clear();
    children2.add(new ExprNodeConstantDesc(4.0));
    children2.add(colDesc2);
    mathFuncExpr.setChildren(children2);
    ve = vc.getVectorExpression(mathFuncExpr);
    Assert.assertEquals(FuncLogWithBaseDoubleToDouble.class, ve.getClass());
    Assert.assertTrue(4 == ((FuncLogWithBaseDoubleToDouble) ve).getBase());

    // Logger with default base
    children2.clear();
    children2.add(colDesc2);
    mathFuncExpr.setChildren(children2);
    ve = vc.getVectorExpression(mathFuncExpr);
    Assert.assertEquals(FuncLnDoubleToDouble.class, ve.getClass());

    //Log with double base
    children2.clear();
    children2.add(new ExprNodeConstantDesc(4.5));
    children2.add(colDesc2);
    mathFuncExpr.setChildren(children2);
    ve = vc.getVectorExpression(mathFuncExpr);
    Assert.assertEquals(FuncLogWithBaseDoubleToDouble.class, ve.getClass());
    Assert.assertTrue(4.5 == ((FuncLogWithBaseDoubleToDouble) ve).getBase());

    //Log with int input and double base
    children2.clear();
    children2.add(new ExprNodeConstantDesc(4.5));
    children2.add(colDesc1);
    mathFuncExpr.setChildren(children2);
    ve = vc.getVectorExpression(mathFuncExpr);
    Assert.assertEquals(FuncLogWithBaseLongToDouble.class, ve.getClass());
    Assert.assertTrue(4.5 == ((FuncLogWithBaseLongToDouble) ve).getBase());

    //Power with double power
    children2.clear();
    children2.add(colDesc2);
    children2.add(new ExprNodeConstantDesc(4.5));
    mathFuncExpr.setGenericUDF(new GenericUDFPower());
    mathFuncExpr.setChildren(children2);
    ve = vc.getVectorExpression(mathFuncExpr);
    Assert.assertEquals(FuncPowerDoubleToDouble.class, ve.getClass());
    Assert.assertTrue(4.5 == ((FuncPowerDoubleToDouble) ve).getPower());

    //Round with default decimal places
    mathFuncExpr.setGenericUDF(udfRound);
    children2.clear();
    children2.add(colDesc2);
    mathFuncExpr.setChildren(children2);
    ve = vc.getVectorExpression(mathFuncExpr);
    Assert.assertEquals(FuncRoundDoubleToDouble.class, ve.getClass());
  }
Create original expression tree for following
(plus (minus (plus col1 col2) col3) (multiply col4 (mod col5 col6)) )
ql/src/test/org/apache/hadoop/hive/ql/exec/vector/TestVectorizationContext.java