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$degreesToRadians (aggregation)

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$degreesToRadians

New in version 4.2.

Converts an input value measured in degrees to radians.

$degreesToRadians has the following syntax:

{ $degreesToRadians: <expression> }

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

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

For more information on expressions, see Expressions.

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

Example
Results
{ $degreesToRadians: NaN }
NaN
{ $degreesToRadians: null }
null
{ $degreesToRadians : Infinity}
Infinity
{ $degreesToRadians : -Infinity }
-Infinity

The trigonometry collection contains a document that contains three angles measured in degrees:

{
"angle_a" : NumberDecimal("53.13010235415597870314438744090659"),
"angle_b" : NumberDecimal("36.86989764584402129685561255909341"),
"angle_c" : NumberDecimal("90")
}

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

db.trigonometry.aggregate([
{
$addFields: {
"angle_a_rad" : { $degreesToRadians : "$angle_a"},
"angle_b_rad" : { $degreesToRadians : "$angle_b"},
"angle_c_rad" : { $degreesToRadians : "$angle_c"}
}
}
])

The operation returns the following document:

{
"_id" : ObjectId("5c50aec71c75c59232b3ede4"),
"angle_a" : NumberDecimal("53.13010235415597870314438744090660"),
"angle_b" : NumberDecimal("36.86989764584402129685561255909341"),
"angle_c" : NumberDecimal("90"),
"angle_a_rad" : NumberDecimal("0.9272952180016122324285124629224290"),
"angle_b_rad" : NumberDecimal("0.6435011087932843868028092287173227"),
"angle_c_rad" : NumberDecimal("1.570796326794896619231321691639752")
}

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

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