Definition
$radiansToDegreesConverts an input value measured in radians to degrees.
$radiansToDegreeshas the following syntax:{ $radiansToDegrees: <expression> }$radiansToDegreestakes any valid expression that resolves to a number.By default
$radiansToDegreesreturns values as adouble.$radiansToDegreescan 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, $radiansToDegrees returns null. If the argument resolves to NaN, $radiansToDegrees returns NaN. If the argument resolves to negative or positive infinity, $radiansToDegrees negative or positive infinity respectively.
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Example
The trigonometry collection contains a document that contains three angles measured in radians:
{ "angle_a" : Decimal128("0.9272952180016122324285124629224290"), "angle_b" : Decimal128("0.6435011087932843868028092287173227"), "angle_c" : Decimal128("1.570796326794896619231321691639752")}The following aggregation operation uses the $radiansToDegrees expression to convert each value to its degree equivalent and add them to the input document using the $addFields pipeline stage.
db.trigangles.aggregate([ { $addFields: { "angle_a_deg" : { $radiansToDegrees : "$angle_a"}, "angle_b_deg" : { $radiansToDegrees : "$angle_b"}, "angle_c_deg" : { $radiansToDegrees : "$angle_c"} } }])The operation returns the following document:
{ "_id" : ObjectId("5c50aec71c75c59232b3ede4"), "angle_a" : Decimal128("0.9272952180016122324285124629224290"), "angle_b" : Decimal128("0.6435011087932843868028092287173227"), "angle_c" : Decimal128("1.570796326794896619231321691639752"), "angle_a_deg" : Decimal128("53.13010235415597870314438744090659"), "angle_b_deg" : Decimal128("36.86989764584402129685561255909341"), "angle_c_deg" : Decimal128("90.00000000000000000000000000000000")}Since angle_a, angle_b, and angle_c are stored as 128-bit decimals, the output of $radiansToDegrees is a 128-bit decimal.