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$atan

New from version 8.0.1.

The $atan operator in Amazon DocumentDB returns the inverse tangent (arc tangent) of a value.

The input expression must resolve to a numeric value.

The result is in radians. To obtain degrees, apply $radiansToDegrees to the output.

The return type is double by default. If the input is a 128-bit decimal, the output is also a 128-bit decimal.

Parameters

Behavior

null and NaN

When the input is null or the referenced field is missing, the result is null. An input of NaN produces NaN.

Example (MongoDB Shell)

The following example shows how to use the $atan operator to calculate the arctangent of a value.

Create sample documents

db.values.insertMany([
  { "_id": 1, "value": 0 },
  { "_id": 2, "value": 1 },
  { "_id": 3, "value": -1 }
]);

Query example

db.values.aggregate([
  { $project: {
    "angle": { $atan: "$value" }
  }}
]);

Output

[
  { "_id": 1, "angle": 0 },
  { "_id": 2, "angle": 0.7853981633974483 },
  { "_id": 3, "angle": -0.7853981633974483 }
]

Code examples

To view a code example for using the $atan operator, choose the tab for the language that you want to use:

Node.js

const { MongoClient } = require('mongodb');

async function main() {
  const client = await MongoClient.connect('mongodb://<username>:<password>@<cluster-endpoint>:27017/?tls=true&tlsCAFile=global-bundle.pem&replicaSet=rs0&readPreference=secondaryPreferred&retryWrites=false');
  const db = client.db('test');
  const collection = db.collection('values');

  const result = await collection.aggregate([
    { $project: {
      "angle": { $atan: "$value" }
    }}
  ]).toArray();

  console.log(result);
  await client.close();
}

main();

Python

from pymongo import MongoClient

def main():
    client = MongoClient('mongodb://<username>:<password>@<cluster-endpoint>:27017/?tls=true&tlsCAFile=global-bundle.pem&replicaSet=rs0&readPreference=secondaryPreferred&retryWrites=false')
    db = client['test']
    collection = db['values']

    result = list(collection.aggregate([
        { '$project': {
            'angle': { '$atan': '$value' }
        }}
    ]))

    print(result)
    client.close()

if __name__ == "__main__":
    main()