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GIS-Distance-0.15
River stage two • 6 direct dependents • 21 total dependents
4 ++
/ GIS::Distance::GreatCircle

NAME

GIS::Distance::GreatCircle - Great circle distance calculations.

DESCRIPTION

A true Great Circle Distance calculation. This was created because the GIS::Distance::MathTrig calculation uses Math::Trig's great_circle_distance() which doesn't actually appear to use the actual Great Circle Distance formula (more like Cosine).

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

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

FORMULA

    c = 2 * asin( sqrt(
        ( sin(( lat1 - lat2 )/2) )**2 + 
        cos( lat1 ) * cos( lat2 ) * 
        ( sin(( lon1 - lon2 )/2) )**2
    ) )

AUTHORS AND LICENSE

See "AUTHORS" in GIS::Distance and "LICENSE" in GIS::Distance.