# Functions for working with geographical coordinates
## greatCircleDistance
Calculate the distance between two points on the Earth's surface using [the great-circle formula](https://en.wikipedia.org/wiki/Great-circle_distance).
-`[(a, b), (c, d) ...]` — Polygon vertices. Data type — [Array](../../data_types/array.md). Each vertex is represented by a pair of coordinates `(a, b)`. Vertices should be specified in a clockwise or counterclockwise order. The minimum number of vertices is 3. The polygon must be constant.
- The function also supports polygons with holes (cut out sections). In this case, add polygons that define the cut out sections using additional arguments of the function. The function does not support non-simply-connected polygons.
**Returned values**
`1` if the point is inside the polygon, `0` if it is not.
If the point is on the polygon boundary, the function may return either 0 or 1.
Encodes latitude and longitude as a geohash-string, please see (http://geohash.org/, https://en.wikipedia.org/wiki/Geohash).
```
geohashEncode(longitude, latitude, [precision])
```
**Input values**
- longitude - longitude part of the coordinate you want to encode. Floating in range`[-180°, 180°]`
- latitude - latitude part of the coordinate you want to encode. Floating in range `[-90°, 90°]`
- precision - Optional, length of the resulting encoded string, defaults to `12`. Integer in range `[1, 12]`. Any value less than `1` or greater than `12` is silently converted to `12`.
**Returned values**
- alphanumeric `String` of encoded coordinate (modified version of the base32-encoding alphabet is used).
**Example**
``` sql
SELECT geohashEncode(-5.60302734375, 42.593994140625, 0) AS res
```
```
┌─res──────────┐
│ ezs42d000000 │
└──────────────┘
```
## geohashDecode
Decodes any geohash-encoded string into longitude and latitude.
**Input values**
- encoded string - geohash-encoded string.
**Returned values**
- (longitude, latitude) - 2-tuple of `Float64` values of longitude and latitude.
Returns an array of geohash-encoded strings of given precision that fall inside and intersect boundaries of given box, basically a 2D grid flattened into array.
**Input values**
- longitude_min - min longitude, floating value in range `[-180°, 180°]`
- latitude_min - min latitude, floating value in range `[-90°, 90°]`
- longitude_max - max longitude, floating value in range `[-180°, 180°]`
- latitude_max - max latitude, floating value in range `[-90°, 90°]`
- precision - geohash precision, `UInt8` in range `[1, 12]`
Please note that all coordinate parameters should be of the same type: either `Float32` or `Float64`.
**Returned values**
- array of precision-long strings of geohash-boxes covering provided area, you should not rely on order of items.
- [] - empty array if *min* values of *latitude* and *longitude* aren't less than corresponding *max* values.
Please note that function will throw an exception if resulting array is over 10'000'000 items long.
**Example**
```
SELECT geohashesInBox(24.48, 40.56, 24.785, 40.81, 4) AS thasos
