Angular distance between points on a sphere.
d = sphdist(long1, lat1, long2, lat2)
long1 = longitude of point 1, scalar or vector
lat1 = latitude of point 1, scalar or vector
long2 = longitude of point 2, scalar or vector
lat2 = latitude of point 2, scalar or vector
Optional Keyword Input Parameters
/DEGREES - means angles are in degrees, else radians.
d = angular distance between points (in radians unless /DEGREES
(1) The procedure GCIRC is similar to SPHDIST(), but may be more
suitable for astronomical applications.
(2) If long1,lat1 are scalars, and long2,lat2 are vectors, then
SPHDIST returns a vector giving the distance of each element of
long2,lat2 to long1,lat1. Similarly, if long1,lat1 are vectors,
and long2, lat2 are scalars, then SPHDIST returns a vector giving
giving the distance of each element of long1,lat1 to to long2,lat2.
If both long1,lat1 and long2,lat2 are vectors then SPHDIST returns
vector giving the distance of each element of long1,lat1 to the
corresponding element of long2, lat2. If the input vectors are
not of equal length, then excess elements of the longer ones will
R. Sterner, 5 Feb, 1991
R. Sterner, 26 Feb, 1991 --- Renamed from sphere_dist.pro
Copyright (C) 1991, Johns Hopkins University/Applied Physics Laboratory
This software may be used, copied, or redistributed as long as it is not
sold and this copyright notice is reproduced on each copy made. This
routine is provided as is without any express or implied warranties
whatsoever. Other limitations apply as described in the file disclaimer.txt.
Converted to IDL V5.0 W. Landsman September 1997