```--- a/inst/km2deg.m
+++ b/inst/km2deg.m
@@ -20,24 +20,30 @@
## @deftypefnx {Function File} {@var{deg} =} km2deg (@var{km}, @var{sphere})
## Convert distance to angle.
##
-## Calculates the angle @var{deg} for a distance @var{km} in a sphere with
+## Calculates the angles @var{deg} for the distances @var{km} in a sphere with
## the mean radius of Earth.
##
## Alternatively, @var{sphere} can be one of "sun", "mercury", "venus", "earth",
## "moon", "mars", "jupiter", "saturn", "uranus", "neptune", or "pluto", in
## which case radius will be set to that object mean radius.
+##
+## @seealso{deg2km}
## @end deftypefn

## Author: Alexander Barth <barth.alexander@gmail.com>

-function a = km2deg (x, radius = "earth")
+function deg = km2deg (km, radius = "earth")
if (nargin < 1 || nargin > 2)
print_usage();
error ("km2deg: RADIUS must be a numeric scalar");
endif
-  a = 180 * x/(pi*radius);
+  deg = 180 * km/(pi*radius);
endfunction
+
+%!assert (deg2km (km2deg (10)), 10)
+%!assert (deg2km (km2deg (10, 80), 80), 10)
+%!assert (deg2km (km2deg (10, "pluto"), "pluto"), 10)
```