$atanh

New from version 8.0.1.

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

The input expression must resolve to a number in the range -1 to 1 (inclusive). Values outside this range cause an error.

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, NaN, and +/- Infinity

When the input is null or the referenced field is missing, the result is null. An input of NaN produces NaN. The boundary values 1 and -1 produce Infinity and -Infinity respectively. Any value outside the [-1, 1] range (including ±Infinity) causes an error.

Example (MongoDB Shell)

The following example shows how to use the $atanh operator to calculate the inverse hyperbolic tangent of a value.

Create sample documents

db.values.insertMany([
  { "_id": 1, "value": 0 },
  { "_id": 2, "value": 0.5 },
  { "_id": 3, "value": -0.5 }
]);

Query example

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

Output

[
  { "_id": 1, "result": 0 },
  { "_id": 2, "result": 0.5493061443340548 },
  { "_id": 3, "result": -0.5493061443340548 }
]

Code examples

To view a code example for using the $atanh 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: {
      "result": { $atanh: "$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([
        { '$project': {
            'result': { '$atanh': '$value' }
        }}
    ]))

    print(result)
    client.close()

if __name__ == "__main__":
    main()