% -*- texinfo -*-
% @deftypefn {Function File} {} specular (@var{sx}, @var{sy}, @var{sz}, @var{l}, @var{v})
% @deftypefnx {Function File} {} specular (@var{sx}, @var{sy}, @var{sz}, @var{l}, @var{v}, @var{se})
% Calculate specular reflection strength of a surface defined by the normal
% vector elements @var{sx}, @var{sy}, @var{sz} using Phong's approximation.
% The light and view vectors can be specified using parameter @var{L} and @var{V} respectively.
% Both can be given as 2-element vectors [azimuth, elevation] in degrees or as 3-element
% vector [x, y, z]. An optional 6th argument describes the specular exponent (spread) @var{se}.
% @seealso{surfl, diffuse}
% @end deftypefn