$exp (aggregation)
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Definition
$exp
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 Expression Operators.
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:
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 }