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• Definition
• Behavior
• Example
\$sin

Returns the sine of a value that is measured in radians.

\$sin has the following syntax:

 { \$sin: }

\$sin takes any valid expression that resolves to a number. If the expression returns a value in degrees, use the \$degreesToRadians operator to convert the result to radians.

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

If the argument resolves to a value of null or refers to a field that is missing, \$sin returns null. If the argument resolves to NaN, \$sin returns NaN. If the argument resolves to negative or positive infinity, \$sin throws an error.

Example
Results
{ \$sin: NaN }
NaN
{ \$sin: null }
null

{ \$sin : Infinity}

or

{ \$sin : -Infinity }

Throws an error message resembling the following formatted output:

 "errmsg" : "Failed to optimize pipeline :: caused by :: cannot apply \$sin to -inf, value must in (-inf,inf)"

The trigonometry collection contains a document that stores the hypotenuse and one angle in a right-angle triangle:

 { "_id" : ObjectId("5c50782193f833234ba90d85"), "angle_a" : NumberDecimal("53.13010235415597870314438744090659"), "hypotenuse" : NumberDecimal("5") }

The following aggregation operation uses the \$sin expression to calculate the side opposite to angle_a and add it to the input document using the \$addFields pipeline stage.

 db.trigonometry.aggregate([ { \$addFields : { "side_b" : { \$multiply : [ { \$sin : {\$degreesToRadians : "\$angle_a"} }, "\$hypotenuse" ] } } } ])

The \$degreesToRadians expression converts the degree value of angle_a to the equivalent value in radians.

The command returns the following output:

 { "_id" : ObjectId("5c50782193f833234ba90d85"), "angle_a" : NumberDecimal("53.13010235415597870314438744090659"), "side_b" : NumberDecimal("4.000000000000000000000000000000000"), "hypotenuse" : NumberDecimal("5"), }

Since angle_a and hypotenuse are stored as 128-bit decimals, the output of \$sin is a 128-bit decimal.

The trigonometry collection contains a document that stores the hypotenuse and one angle in a right-angle triangle:

 { "_id" : ObjectId("5c50782193f833234ba90d85"), "angle_a" : NumberDecimal("0.9272952180016122324285124629224288"), "hypotenuse" : NumberDecimal("5") }

The following aggregation operation uses the \$sin expression to calculate the side opposite to angle_a and add it to the input document using the \$addFields pipeline stage.

 db.trigonometry.aggregate([ { \$addFields : { "side_b" : { \$multiply : [ { \$sin : "\$angle_a" }, "\$hypotenuse" ] } } } ])

The command returns the following output:

 { "_id" : ObjectId("5c50782193f833234ba90d85"), "angle_a" : NumberDecimal("0.9272952180016122324285124629224288"), "side_b" : NumberDecimal("4.000000000000000000000000000000000"), "hypotenuse" : NumberDecimal("5"), }

Since angle_a and hypotenuse are stored as 128-bit decimals, the output of \$sin is a 128-bit decimal.