Introduction to MongoDB $asin Operator

The Mongodb $asin operator is an inverse sine function used to calculate the arcsine value of a given number and return its radian value.

Syntax

The syntax of the $asin operator is as follows:

{ $asin: <number> }

Here, <number> is the number for which the arcsine value is to be calculated.

Use Cases

The $asin operator is typically used in scenarios that require the calculation of arcsine values, such as calculating angles or rotation angles between two points.

Example

Assume that there is a students collection in a Mongodb database that contains the following documents:

{ "_id": 1, "name": "Alice", "math": 90, "physics": 80 }
{ "_id": 2, "name": "Bob", "math": 80, "physics": 85 }
{ "_id": 3, "name": "Charlie", "math": 85, "physics": 75 }

Now, suppose we want to calculate the arcsine values of the math and physics scores for each student. We can use the following aggregation pipeline to achieve this:

db.students.aggregate([
  {
    $project: {
      name: 1,
      math_asin: { $asin: { $divide: ["$math", 100] } },
      physics_asin: { $asin: { $divide: ["$physics", 100] } }
    }
  }
])

In the example above, the $project operator is used first to select the fields to be returned, including the name and the arcsine values of the math and physics scores. Then, the $asin operator is used to calculate the arcsine values of the math and physics scores and store them in new fields math_asin and physics_asin. Finally, the result is returned as follows:

{ "_id" : 1, "name" : "Alice", "math_asin" : 1.4706289056333368, "physics_asin" : 1.2701822420595373 }
{ "_id" : 2, "name" : "Bob", "math_asin" : 1.2915436464758038, "physics_asin" : 1.3033188878487208 }
{ "_id" : 3, "name" : "Charlie", "math_asin" : 1.3229048614910654, "physics_asin" : 1.1423977486769688 }

In the above result, the arcsine values of the math and physics scores for each student have been calculated.

Conclusion

The Mongodb $asin operator is a convenient inverse sine function that can be used to calculate the arcsine value of a given number and return its radian value. It is typically used in scenarios that require the calculation of angles or rotation angles. When using it, it should be noted that the input number should be within the range of -1 to 1.