Database Manual / Reference / Query Language / Expressions

$cosh (expression operator)（表达式运算符）

$cosh

Returns the hyperbolic cosine of a value that is measured in radians.返回以弧度为单位的值的双曲余弦。

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

{ $cosh: <expression> }

$cosh takes any valid expression that resolves to a number, measured in radians. 接受解析为数字（以弧度为单位）的任何有效表达式。If the expression returns a value in degrees, use the $degreesToRadians operator to convert the value to radians.如果表达式返回以度为单位的值，请使用$degreesToRadians运算符将该值转换为弧度。

By default $cosh returns values as a double. $cosh can also return values as a 128-bit decimal if the <expression> resolves to a 128-bit decimal value.默认情况下，$cosh返回double值。如果<expression>解析为128位十进制值，$cosh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 +/- Infinitynull、NaN和+/- Infinity

If the input argument resolves to a value of null or refers to a field that is missing, $cosh returns null. 如果输入参数解析为null值或引用缺少的字段，$cosh将返回null。If the argument resolves to NaN, $cosh returns NaN. 如果参数解析为NaN，$cosh将返回NaN。If the argument resolves to negative or positive Infinity, $cosh returns positive Infinity.如果参数解析为负无穷大或正无穷大，$cosh将返回正无穷大。

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

Example示例

Hyperbolic Cosine in Degrees以度为单位的双曲余弦

The following trigonometry collection contains a document that stores an angle value measured in degrees:以下trigonometry集合包含一个存储以度为单位测量的angle值的文档：

db.trigonometry.insertOne(
   {
      "_id" : ObjectId( "5c50782193f833234ba90d85" ),
      "angle" : Decimal128( "53.1301023541559787031443874490659" )
   }
)

The following aggregation operation uses the $cosh expression to calculate the hyperbolic cosine of angle and adds it to the input document using the $addFields pipeline stage:以下聚合操作使用$cosh表达式计算角度的双曲余弦，并使用$addFields管道阶段将其添加到输入文档中：

db.trigonometry.aggregate( [
   {
      $addFields : {
         "cosh_output" : { $cosh : { $degreesToRadians : "$angle" } }
      }
   }
] )

The $degreesToRadians expression converts the angle in degrees to radians.$degreesToRadians表达式将角度（度）转换为弧度。

Example output:示例输出：

{
   "_id" : ObjectId("5c50782193f833234ba90d85"),
   "angle" : Decimal128("53.1301023541559787031443874490659"),
   "cosh_output" : Decimal128("1.461642741099671277595921778079396")
}

Because angle is stored as a 128-bit decimal, the $cosh output is also a 128-bit decimal.因为angle存储为128位十进制，所以$cosh输出也是128位十进制。

Hyperbolic Cosine in Radians以弧度为单位的双曲余弦

The following trigonometry collection contains a document that stores an angle value measured in radians:以下trigonometry集合包含一个文档，其中存储了以弧度为单位测量的angle值：

db.trigonometry.insertOne(
   {
      "_id" : ObjectId( "5c50782193f833234ba90d15" ),
      "angle" : Decimal128( "1.6301023541559787031443874490659" )
   }
)

The following aggregation operation uses the $cosh expression to calculate the hyperbolic cosine of angle and adds it to the input document using the $addFields pipeline stage:以下聚合操作使用$cosh表达式计算角度的双曲余弦，并使用$addFields管道阶段将其添加到输入文档中：

db.trigonometry.aggregate( [
   {
      $addFields : {
         "cosh_output" : { $cosh : "$angle" }
      }
   }
] )

Example output:示例输出：

{
   "_id" : ObjectId("5c50782193f833234ba90d15"),
   "angle" : Decimal128("1.6301023541559787031443874490659"),
   "cosh_output" : Decimal128("2.650153334504361016712328539738000")
}

Because angle is stored as a 128-bit decimal, the $cosh output is also a 128-bit decimal.因为angle存储为128位十进制，所以$cosh输出也是128位十进制。