- Reference >
- Operators >
- Aggregation Pipeline Operators >
- Arithmetic Aggregation Operators >
- $exp (aggregation)
$exp (aggregation)¶
On this page
Definition¶
-
$exp¶ New in version 3.2.
Raises Euler’s number (i.e. e ) to the specified exponent and returns the result.
$exphas the following syntax:{ $exp: <exponent> }
The
<exponent>expression can be any valid expression as long as it resolves to a number. For more information on expressions, see Expressions.
Behavior¶
If the argument resolves to a value of null or refers to a field that is
missing, $exp returns null. If the argument resolves to
NaN, $exp returns NaN.
| Example | Results |
|---|---|
{ $exp: 0 } |
1 |
{ $exp: 2 } |
7.38905609893065 |
{ $exp: -2 } |
0.1353352832366127 |
Example¶
A collection named accounts contains the following documents:
{ _id: 1, rate: .08, pv: 10000 }
{ _id: 2, rate: .0825, pv: 250000 }
{ _id: 3, rate: .0425, pv: 1000 }
The following example calculates the effective interest rate for continuous compounding:
db.accounts.aggregate( [ { $project: { effectiveRate: { $subtract: [ { $exp: "$rate"}, 1 ] } } } ] )
The operation returns the following results:
{ "_id" : 1, "effectiveRate" : 0.08328706767495864 }
{ "_id" : 2, "effectiveRate" : 0.08599867343905654 }
{ "_id" : 3, "effectiveRate" : 0.04341605637367807 }