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$exp (aggregation)

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  • Definition
  • Behavior
  • Example
$exp

New in version 3.2.

Raises Euler's number (i.e. e ) to the specified exponent and returns the result.

$exp has 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.

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

A collection named accounts contains the following documents:

db.accounts.insertMany( [
{ _id: 1, interestRate: .08, presentValue: 10000 },
{ _id: 2, interestRate: .0825, presentValue: 250000 },
{ _id: 3, interestRate: .0425, presentValue: 1000 }
] )

The following example calculates the effective interest rate for continuous compounding:

db.accounts.aggregate( [ { $project: { effectiveRate: { $subtract: [ { $exp: "$interestRate"}, 1 ] } } } ] )

The operation returns the following results:

{ "_id" : 1, "effectiveRate" : 0.08328706767495864 }
{ "_id" : 2, "effectiveRate" : 0.08599867343905654 }
{ "_id" : 3, "effectiveRate" : 0.04341605637367807 }
← $eq (aggregation)