1 files changed, 62 insertions, 0 deletions
diff --git a/inst/rad2sm.m b/inst/rad2sm.m
new file mode 100644
index 0000000..917e758
--- /dev/null
+++ b/inst/rad2sm.m
@@ -0,0 +1,62 @@
+## Copyright (C) 2014-2020 Pooja Rao
+## Copyright (C) 2018-2020 Philip Nienhuis
+##
+## This program is free software; you can redistribute it and/or modify it under
+## the terms of the GNU General Public License as published by the Free Software
+## Foundation; either version 3 of the License, or (at your option) any later
+## version.
+##
+## This program is distributed in the hope that it will be useful, but WITHOUT
+## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+## FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+## details.
+##
+## You should have received a copy of the GNU General Public License along with
+## this program; if not, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn  {Function File} {@var{sm} =} rad2sm (@var{rad})
+## @deftypefnx {Function File} {@var{sm} =} rad2sm (@var{rad}, @var{radius})
+## @deftypefnx {Function File} {@var{sm} =} rad2sm (@var{rad}, @var{sphere})
+## Converts angle in radians to distance in statute miles by multiplying angle
+## with radius.
+##
+## Calculates the distances @var{sm} in a sphere with @var{radius} (also in
+## statute miles) for the angles @var{rad}.  If unspecified, radius defaults to
+## 3958 sm, 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's mean radius.
+##
+## @seealso{deg2km, deg2nm, deg2sm, km2rad, km2deg,
+## nm2deg, nm2rad, rad2km, rad2nm, sm2deg, sm2rad}
+## @end deftypefn
+
+## Built with insight from
+## Author: Pooja Rao <poojarao12@gmail.com>
+## Adapted from deg2km.m by Anonymous contributor, see patch #9709
+
+function sm = rad2sm (rad, radius = "earth")
+
+  ## Check arguments
+  if (nargin < 1 || nargin > 2)
+    print_usage();
+  elseif (ischar (radius))
+    ## Get radius of sphere with its default units (km)
+    radius = km2sm (spheres_radius (radius));
+  ## Check input
+  elseif (! isnumeric (radius) || ! isreal (radius))
+    error ("rad2sm: RADIUS must be a numeric scalar");
+  endif
+  sm = (rad * radius);
+
+endfunction
+
+
+%!test
+%!assert (sm2rad (rad2sm (10)), 10, 10*eps);
+%!assert (sm2rad (rad2sm (10, 80), 80), 10, 10*eps);
+%!assert (sm2rad (rad2sm (10, "pluto"), "pluto"), 10, 10*eps);
+
+%!error <RADIUS> rad2sm (5, 5i)