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## 算数运算符和函数

### 算数运算符

#### 一元算数运算符

支持的运算符：`+`, `-`

输入数据类型要求：`INT32`, `INT64`, `FLOAT`, `DOUBLE`

输出数据类型：与输入数据类型一致

#### 二元算数运算符

支持的运算符：`+`, `-`, `*`, `/`,  `%`

输入数据类型要求：`INT32`, `INT64`, `FLOAT`和`DOUBLE`

输出数据类型：`DOUBLE`

注意：当某个时间戳下左操作数和右操作数都不为空（`null`）时，二元运算操作才会有输出结果

#### 使用示例

例如：

```sql
select s1, - s1, s2, + s2, s1 + s2, s1 - s2, s1 * s2, s1 / s2, s1 % s2 from root.sg.d1
```

结果：

``` 
+-----------------------------+-------------+--------------+-------------+-------------+-----------------------------+-----------------------------+-----------------------------+-----------------------------+-----------------------------+
|                         Time|root.sg.d1.s1|-root.sg.d1.s1|root.sg.d1.s2|root.sg.d1.s2|root.sg.d1.s1 + root.sg.d1.s2|root.sg.d1.s1 - root.sg.d1.s2|root.sg.d1.s1 * root.sg.d1.s2|root.sg.d1.s1 / root.sg.d1.s2|root.sg.d1.s1 % root.sg.d1.s2|
+-----------------------------+-------------+--------------+-------------+-------------+-----------------------------+-----------------------------+-----------------------------+-----------------------------+-----------------------------+
|1970-01-01T08:00:00.001+08:00|          1.0|          -1.0|          1.0|          1.0|                          2.0|                          0.0|                          1.0|                          1.0|                          0.0|
|1970-01-01T08:00:00.002+08:00|          2.0|          -2.0|          2.0|          2.0|                          4.0|                          0.0|                          4.0|                          1.0|                          0.0|
|1970-01-01T08:00:00.003+08:00|          3.0|          -3.0|          3.0|          3.0|                          6.0|                          0.0|                          9.0|                          1.0|                          0.0|
|1970-01-01T08:00:00.004+08:00|          4.0|          -4.0|          4.0|          4.0|                          8.0|                          0.0|                         16.0|                          1.0|                          0.0|
|1970-01-01T08:00:00.005+08:00|          5.0|          -5.0|          5.0|          5.0|                         10.0|                          0.0|                         25.0|                          1.0|                          0.0|
+-----------------------------+-------------+--------------+-------------+-------------+-----------------------------+-----------------------------+-----------------------------+-----------------------------+-----------------------------+
Total line number = 5
It costs 0.014s
```

### 数学函数

目前 IoTDB 支持下列数学函数，这些数学函数的行为与这些函数在 Java Math 标准库中对应实现的行为一致。

| 函数名  | 输入序列类型                   | 输出序列类型             | 必要属性参数    | Java 标准库中的对应实现                                      |
| ------- | ------------------------------ | ------------------------ |-----------| ------------------------------------------------------------ |
| SIN     | INT32 / INT64 / FLOAT / DOUBLE | DOUBLE                   |           | Math#sin(double)                                             |
| COS     | INT32 / INT64 / FLOAT / DOUBLE | DOUBLE                   |           | Math#cos(double)                                             |
| TAN     | INT32 / INT64 / FLOAT / DOUBLE | DOUBLE                   |           | Math#tan(double)                                             |
| ASIN    | INT32 / INT64 / FLOAT / DOUBLE | DOUBLE                   |           | Math#asin(double)                                            |
| ACOS    | INT32 / INT64 / FLOAT / DOUBLE | DOUBLE                   |           | Math#acos(double)                                            |
| ATAN    | INT32 / INT64 / FLOAT / DOUBLE | DOUBLE                   |           | Math#atan(double)                                            |
| SINH    | INT32 / INT64 / FLOAT / DOUBLE | DOUBLE                   |           | Math#sinh(double)                                            |
| COSH    | INT32 / INT64 / FLOAT / DOUBLE | DOUBLE                   |           | Math#cosh(double)                                            |
| TANH    | INT32 / INT64 / FLOAT / DOUBLE | DOUBLE                   |           | Math#tanh(double)                                            |
| DEGREES | INT32 / INT64 / FLOAT / DOUBLE | DOUBLE                   |           | Math#toDegrees(double)                                       |
| RADIANS | INT32 / INT64 / FLOAT / DOUBLE | DOUBLE                   |           | Math#toRadians(double)                                       |
| ABS     | INT32 / INT64 / FLOAT / DOUBLE | 与输入序列的实际类型一致 |           | Math#abs(int) / Math#abs(long) /Math#abs(float) /Math#abs(double) |
| SIGN    | INT32 / INT64 / FLOAT / DOUBLE | DOUBLE                   |           | Math#signum(double)                                          |
| CEIL    | INT32 / INT64 / FLOAT / DOUBLE | DOUBLE                   |           | Math#ceil(double)                                            |
| FLOOR   | INT32 / INT64 / FLOAT / DOUBLE | DOUBLE                   |           | Math#floor(double)                                           |
| ROUND   | INT32 / INT64 / FLOAT / DOUBLE | DOUBLE                   |`places`:四舍五入有效位数，正数为小数点后面的有效位数，负数为整数位的有效位数 | Math#rint(Math#pow(10,places))/Math#pow(10,places)|
| EXP     | INT32 / INT64 / FLOAT / DOUBLE | DOUBLE                   |           | Math#exp(double)                                             |
| LN      | INT32 / INT64 / FLOAT / DOUBLE | DOUBLE                   |           | Math#log(double)                                             |
| LOG10   | INT32 / INT64 / FLOAT / DOUBLE | DOUBLE                   |           | Math#log10(double)                                           |
| SQRT    | INT32 / INT64 / FLOAT / DOUBLE | DOUBLE                   |           | Math#sqrt(double)                                            |

例如：

```   sql
select s1, sin(s1), cos(s1), tan(s1) from root.sg1.d1 limit 5 offset 1000;
```

结果：

```
+-----------------------------+-------------------+-------------------+--------------------+-------------------+
|                         Time|     root.sg1.d1.s1|sin(root.sg1.d1.s1)| cos(root.sg1.d1.s1)|tan(root.sg1.d1.s1)|
+-----------------------------+-------------------+-------------------+--------------------+-------------------+
|2020-12-10T17:11:49.037+08:00|7360723084922759782| 0.8133527237573284|  0.5817708713544664| 1.3980636773094157|
|2020-12-10T17:11:49.038+08:00|4377791063319964531|-0.8938962705202537|  0.4482738644511651| -1.994085181866842|
|2020-12-10T17:11:49.039+08:00|7972485567734642915| 0.9627757585308978|-0.27030138509681073|-3.5618602479083545|
|2020-12-10T17:11:49.040+08:00|2508858212791964081|-0.6073417341629443| -0.7944406950452296| 0.7644897069734913|
|2020-12-10T17:11:49.041+08:00|2817297431185141819|-0.8419358900502509| -0.5395775727782725| 1.5603611649667768|
+-----------------------------+-------------------+-------------------+--------------------+-------------------+
Total line number = 5
It costs 0.008s
```
#### ROUND
例如：
```sql
select s4,round(s4),round(s4,2),round(s4,-1) from root.sg1.d1 
```

```sql
+-----------------------------+-------------+--------------------+----------------------+-----------------------+
|                         Time|root.db.d1.s4|ROUND(root.db.d1.s4)|ROUND(root.db.d1.s4,2)|ROUND(root.db.d1.s4,-1)|
+-----------------------------+-------------+--------------------+----------------------+-----------------------+
|1970-01-01T08:00:00.001+08:00|    101.14345|               101.0|                101.14|                  100.0|
|1970-01-01T08:00:00.002+08:00|    20.144346|                20.0|                 20.14|                   20.0|
|1970-01-01T08:00:00.003+08:00|    20.614372|                21.0|                 20.61|                   20.0|
|1970-01-01T08:00:00.005+08:00|    20.814346|                21.0|                 20.81|                   20.0|
|1970-01-01T08:00:00.006+08:00|     60.71443|                61.0|                 60.71|                   60.0|
|2023-03-13T16:16:19.764+08:00|    10.143425|                10.0|                 10.14|                   10.0|
+-----------------------------+-------------+--------------------+----------------------+-----------------------+
Total line number = 6
It costs 0.059s
```