Definition
- $degreesToRadians
- New in version 4.2. - Converts an input value measured in degrees to radians. - $degreesToRadianshas the following syntax:- { $degreesToRadians: <expression> } - $degreesToRadianstakes any valid expression that resolves to a number.- By default - $degreesToRadiansreturns values as a- double.- $degreesToRadianscan 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. 
Behavior
null, NaN, and +/- Infinity
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.
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Example
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.