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$radiansToDegrees（表达式操作符）

定义

$radiansToDegrees

将以弧度为单位测量的输入值转换为度数。

$radiansToDegrees 通过以下语法实现：

{ $radiansToDegrees: <expression> }

$radiansToDegrees takes any valid expression that resolves to a number.

By default $radiansToDegrees returns values as a double. $radiansToDegrees can also return values as a 128-bit decimal as long as the <expression> resolves to a 128-bit decimal value.

有关表达式的更多信息，请参阅表达式。

行为

`null`、`NaN` 和`+/- Infinity`

If the argument resolves to a value of null or refers to a field that is missing, $radiansToDegrees returns null. If the argument resolves to NaN, $radiansToDegrees returns NaN. If the argument resolves to negative or positive infinity, $radiansToDegrees negative or positive infinity respectively.

例子	结果
`{ $radiansToDegrees: NaN }`	`NaN`
`{ $radiansToDegrees: null }`	`null`
`{ $radiansToDegrees : Infinity}`	`Infinity`
`{ $radiansToDegrees : -Infinity }`	`-Infinity`

例子

trigonometry集合包含一个文档，其中包含三个以弧度为单位的角度：

{
  "angle_a" : Decimal128("0.9272952180016122324285124629224290"),
  "angle_b" : Decimal128("0.6435011087932843868028092287173227"),
  "angle_c" : Decimal128("1.570796326794896619231321691639752")
}

The following aggregation operation uses the $radiansToDegrees expression to convert each value to its degree equivalent and add them to the input document using the $addFields pipeline stage.

db.trigangles.aggregate([
  {
    $addFields: {
      "angle_a_deg" : { $radiansToDegrees : "$angle_a"},
      "angle_b_deg" : { $radiansToDegrees : "$angle_b"},
      "angle_c_deg" : { $radiansToDegrees : "$angle_c"}
    }
  }
])

该操作将返回以下文档：

{
  "_id" : ObjectId("5c50aec71c75c59232b3ede4"),
  "angle_a" : Decimal128("0.9272952180016122324285124629224290"),
  "angle_b" : Decimal128("0.6435011087932843868028092287173227"),
  "angle_c" : Decimal128("1.570796326794896619231321691639752"),
  "angle_a_deg" : Decimal128("53.13010235415597870314438744090659"),
  "angle_b_deg" : Decimal128("36.86989764584402129685561255909341"),
  "angle_c_deg" : Decimal128("90.00000000000000000000000000000000")
}

Since angle_a, angle_b, and angle_c are stored as 128-bit decimals, the output of $radiansToDegrees is a 128-bit decimal.

$radiansToDegrees（表达式操作符）

定义

行为

null、NaN 和+/- Infinity

例子

`null`、`NaN` 和`+/- Infinity`