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

SUPPORT

See "SUPPORT" in GIS::Distance.

AUTHORS

See "AUTHORS" in GIS::Distance.

COPYRIGHT AND LICENSE

See "COPYRIGHT AND LICENSE" in GIS::Distance.