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$cos (aggregation)

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Definition

$cos

New in version 4.2.

Returns the cosine of a value that is measured in radians.

$cos has the following syntax:

{ $cos: <expression> }

$cos takes any valid expression that resolves to a number. If the expression returns a value in degrees, use the $degreesToRadians operator to convert the result to radians.

By default $cos returns values as a double. $cos 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

null, NaN, and +/- Infinity

If the argument resolves to a value of null or refers to a field that is missing, $cos returns null. If the argument resolves to NaN, $cos returns NaN. If the argument resolves to negative or positive infinity, $cos throws an error.

ExampleResults
{ $cos: NaN }NaN
{ $cos: null }null
{ $cos : Infinity}
or
{ $cos : -Infinity } 		Throws an error message resembling the following formatted output: 
"errmsg" :
  "Failed to optimize pipeline :: caused by :: cannot
  apply $cos to -inf, value must in (-inf,inf)"

Example