Database Manual / Reference / Query Language / Expressions

$asinh (expression operator)（表达式运算符）

$asinh

Returns the inverse hyperbolic sine (hyperbolic arc sine) of a value.返回一个值的反双曲正弦（双曲弧正弦）。

$asinh has the following syntax:具有以下语法：

{ $asinh: <expression> }

$asinh takes any valid expression that resolves to a number.$asinh接受任何解析为数字的有效表达式。

$asinh returns values in radians. 返回以弧度为单位的值。Use $radiansToDegrees operator to convert the output value from radians to degrees.使用$radiasToDegrees运算符将输出值从弧度转换为度数。

By default $asinh returns values as a double. $asinh can also return values as a 128-bit decimal as long as the <expression> resolves to a 128-bit decimal value.默认情况下，$asinh返回double值。只要<expression>解析为128位十进制值，$asinh也可以返回128位十进制的值。

For more information on expressions, see Expressions.有关表达式的详细信息，请参阅表达式。

Behavior行为

null, NaN, and +/- Infinity

If the argument resolves to a value of null or refers to a field that is missing, $asinh returns null. 如果参数解析为null值或引用缺少的字段，$asinh将返回null。If the argument resolves to NaN, $asinh returns NaN. 如果参数解析为NaN，$asinh将返回NaN。If the argument resolves to negative or positive infinity, $asinh returns negative or positive infinity respectively.如果参数解析为负无穷大或正无穷大，$asinh将分别返回负无穷大和正无穷大。

Example示例Results结果
{ $asinh: NaN }NaN
{ $asinh: null }null
{ $asinh : Infinity}Infinity
{ $asinh : -Infinity }-Infinity

Example示例

Inverse Hyperbolic Sine in Degrees以度为单位的逆双曲正弦

The trigonometry collection contains a document that stores a value along the x axis of a 2-D graph:trigonometry集合包含一个文档，该文档存储了沿二维图x轴的值：

{
  "_id" : ObjectId("5c50782193f833234ba90d85"),
  "x-coordinate" : Decimal128("1")
}

The following aggregation operation uses the $asinh expression to calculate inverse hyperbolic sine of x-coordinate and add it to the input document using the $addFields pipeline stage.以下聚合操作使用$asinh表达式计算x-coordinate的反双曲正弦，并使用$addFields管道阶段将其添加到输入文档中。

db.trigonometry.aggregate([
  {
    $addFields : {
      "y-coordinate" : {
        $radiansToDegrees : { $asinh : "$x-coordinate" }
      }
    }
  }
])

The $radiansToDegrees expression converts the radian value returned by $asinh to the equivalent value in degrees.$radiasToDegrees表达式将$asinh返回的弧度值转换为以度为单位的等效值。

The command returns the following output:该命令返回以下输出：

{
  "_id" : ObjectId("5c50782193f833234ba90d85"),
  "x-coordinate" : Decimal128("1"),
  "y-coordinate" : Decimal128("50.49898671052621144221476300417157")
}

Since x-coordinate is stored as a 128-bit decimal, the output of $asinh is a 128-bit decimal.由于x-coordinate存储为128位十进制，因此$asinh的输出是128位十进制。

Inverse Hyperbolic Sine in Radians以弧度为单位的逆双曲正弦

The trigonometry collection contains a document that stores a value along the x axis of a 2-D graph:trigonometry集合包含一个文档，该文档存储了沿二维图x轴的值：

{
  "_id" : ObjectId("5c50782193f833234ba90d85"),
  "x-coordinate" : Decimal128("1")
}

The following aggregation operation uses the $asinh expression to calculate inverse hyperbolic sine of x-coordinate and add it to the input document using the $addFields pipeline stage.以下聚合操作使用$asinh表达式计算x坐标的反双曲正弦，并使用$addFields管道阶段将其添加到输入文档中。

db.trigonometry.aggregate([
  {
    $addFields : {
      "y-coordinate" : {
        $asinh : "$x-coordinate"
      }
    }
  }
])

The command returns the following output:该命令返回以下输出：

{
  "_id" : ObjectId("5c50782193f833234ba90d85"),
  "x-coordinate" : Decimal128("1"),
  "y-coordinate" : Decimal128("1.818446459232066823483698963560709")
}

Since x-coordinate is stored as a 128-bit decimal, the output of $asinh is a 128-bit decimal.由于x-coordinate存储为128位十进制，因此$asinh的输出是128位十进制。