$asin (aggregation)
$asin
Returns the inverse sine (arc sine) of a value.
$asin
has the following syntax:{ $asin: <expression> } $asin
takes any valid expression that resolves to a number between-1
and1
, e.g.-1 <= value <= 1
.$asin
returns values in radians. Use$radiansToDegrees
operator to convert the output value from radians to degrees.By default
$asin
returns values as adouble
.$asin
can also return values as a 128-bit decimal as long as the<expression>
resolves to a 128-bit decimal value.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, $asin
returns null
. If the
argument resolves to NaN
, $asin
returns NaN
.
If the argument resolves to a value outside the bounds of
[-1, 1]
inclusive, $asin
throws an error.
Example | Results | |||
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or
| Throws an error message resembling the following formatted output:
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Example
The trigonometry
collection contains a document that
stores three sides of a right-angle triangle:
{ "_id" : ObjectId("5c50782193f833234ba90d85"), "side_a" : NumberDecimal("3"), "side_b" : NumberDecimal("4"), "hypotenuse" : NumberDecimal("5") }
The following aggregation operation uses the
$asin
expression to calculate the angle opposite
to side_a
and add it to the input document using the
$addFields
pipeline stage.
db.trigonometry.aggregate([ { $addFields : { "angle_a" : { $radiansToDegrees : { $asin : { $divide : [ "$side_a", "$hypotenuse" ] } } } } } ])
The $radiansToDegrees
expression converts the
radian value returned by $asin
to the equivalent
value in degrees.
The command returns the following output:
{ "_id" : ObjectId("5c50782193f833234ba90d85"), "side_a" : NumberDecimal("3"), "side_b" : NumberDecimal("4"), "hypotenuse" : NumberDecimal("5"), "angle_a" : NumberDecimal("36.86989764584402129685561255909341") }
Since side_a
and hypotenuse
are stored as
128-bit decimals, the output of
$asin
is a 128-bit decimal.
The trigonometry
collection contains a document that
stores three sides of a right-angle triangle:
{ "_id" : ObjectId("5c50782193f833234ba90d85"), "side_a" : NumberDecimal("3"), "side_b" : NumberDecimal("4"), "hypotenuse" : NumberDecimal("5") }
The following aggregation operation uses the
$asin
expression to calculate the angle adjacent
to side_a
and add it to the input document using the
$addFields
pipeline stage.
db.trigonometry.aggregate([ { $addFields : { "angle_a" : { $asin : { $divide : [ "$side_a", "$hypotenuse" ] } } } } ])
The command returns the following output:
{ "_id" : ObjectId("5c50782193f833234ba90d85"), "side_a" : NumberDecimal("3"), "side_b" : NumberDecimal("4"), "hypotenuse" : NumberDecimal("5"), "angle_a" : NumberDecimal("0.6435011087932843868028092287173226") }
Since side_a
and hypotenuse
are stored as
128-bit decimals, the output of
$asin
is a 128-bit decimal.