# Haversine formula

```ruby
class EarthPoint(lat, lon) {

    const earth_radius = 6371       # mean earth radius
    const radian_ratio = Num.pi/180

    # accessors for radians
    method latR { self.lat * radian_ratio }
    method lonR { self.lon * radian_ratio }

    method haversine_dist(EarthPoint p) {
        var arc = EarthPoint(
              self.lat - p.lat,
              self.lon - p.lon,
        )

        var a = Math.sum(
                  (arc.latR / 2).sin**2,
                  (arc.lonR / 2).sin**2 *
                    self.latR.cos * p.latR.cos
                )

        earth_radius * a.sqrt.asin * 2
    }
}

var BNA = EarthPoint.new(lat: 36.12, lon: -86.67)
var LAX = EarthPoint.new(lat: 33.94, lon: -118.4)

say BNA.haversine_dist(LAX)   #=> 2886.444442837983299747157823945746716...
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://trizen.gitbook.io/sidef-lang/programming_tasks/h/haversine_formula.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.