---
name: "GIS::Distance::Cosine"
section: "3pm"
platform: "linux"
package: "libgis-distance-perl"
version: "0.20-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/GIS::Distance::Cosine"
---

# GIS::Distance::Cosine(3pm)

Spherical law of cosines distance calculations.

## NAME

GIS::Distance::Cosine - Spherical law of cosines distance calculations.

## DESCRIPTION

Although this formula is mathematically exact, it is unreliable for small distances.  See GIS::Distance::MathTrig for related details.

A faster (XS) version of this formula is available as GIS::Distance::Fast::Cosine.

Normally this module is not used directly.  Instead GIS::Distance is used which in turn interfaces with the various formula classes.

## FORMULA

```
    a = sin(lat1) * sin(lat2)
    b = cos(lat1) * cos(lat2) * cos(lon2 - lon1)
    c = arccos(a + b)
    d = R * c
```

## SEE ALSO

- •

  \<https://en.wikipedia.org/wiki/Spherical\_law\_of\_cosines\>

## SUPPORT

See "SUPPORT" in GIS::Distance.

## AUTHORS

See "AUTHORS" in GIS::Distance.

## LICENSE

See "LICENSE" in GIS::Distance.