Aran Clary Deltac > GIS-Distance-0.08 > GIS::Distance::Formula::Cosine

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Module Version: 0.08   Source  

NAME ^

GIS::Distance::Formula::Cosine - Cosine distance calculations.

DESCRIPTION ^

Although this formula is mathematically exact, it is unreliable for small distances because the inverse cosine is ill-conditioned.

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

METHODS ^

distance

This method is called by GIS::Distance's distance() method.

SEE ALSO ^

GIS::Distanc

GIS::Distance::Formula::Cosine::Fast

AUTHOR ^

Aran Clary Deltac <bluefeet@cpan.org>

LICENSE ^

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

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