dist_functions: Distance measures available in distance
Description
The great circle distance is calculated by the function rdist.earth in library fields.Details
The distance measures implemented in sphet are:
'euclidean':$\sqrt{\sum{(x_i - y_i)^2}}$'chebyshev':$max(|x_i - y_i|)$'braycur':$\frac{\sum{|x_i - y_i|}}{\sum{|x_i + y_i|}}$'canberra':$\frac{\sum{|x_i - y_i|}}{\sum{|x_i| + |y_i|}}$'gcircle': seerdist.earth.