posdist

Calculates distance in km between two points given in decimal degrees latitude and longitude. Calculation can be great circle distance (smallest distance along the surface of a sphere) or Cartesian distance (planar approximation for smaller distances).
Input can be as scalars or arrays, as long as dimensions are identical for all four coordinates.

The function is based on the pos2dist function submitted by Langqui Sun, modified to allow arrays as input.