# \$1exp
<a name="exp"></a>

New from version 4.0

The `$exp` operator in Amazon DocumentDB allows you to raise the constant e to a given number.

**Parameters**
+ `expression`: The expression to evaluate. This can be any valid aggregation expression, including field references, arithmetic operations, and other aggregation stages.

## Example (MongoDB Shell)
<a name="exp-examples"></a>

The following example demonstrates the use of the `$exp` operator to find all documents where the `quantity` field is greater than the `price` field.

**Create sample documents**

```
db.items.insertMany([
  { item: "canvas", quantity: 4 },
  { item: "journal", quantity: 2 }
]);
```

**Query example**

```
db.items.aggregate([
  { $project: {
    "quantityRaised": {$exp: "$quantity"}}
  }
]);
```

**Output**

```
[
  {
    _id: ObjectId('6920b785311cf98b79d2950d'),
    quantityRaised: 54.598150033144236
  },
  {
    _id: ObjectId('6920b785311cf98b79d2950e'),
    quantityRaised: 7.38905609893065
  }
]
```

## Code examples
<a name="exp-code"></a>

To view a code example for using the `$exp` command, choose the tab for the language that you want to use:

------
#### [ Node.js ]

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

async function aggregateExp() {
  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 items = db.collection('items');

  const result = await items.aggregate([
    { $project: {
      "quantityRaised": {$exp: "$quantity"}}
    }
    ]).toArray();

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

aggregateExp();
```

------
#### [ Python ]

```
from pymongo import MongoClient

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

    result = list(items.aggregate([
      { "$project": {
        "quantityRaised": {"$exp": "$quantity"}}
      }
    ]))

    print(result)
    client.close()

aggregate_exp()
```

------