% -*- texinfo -*-
% @deftypefn {Function File} {} diffuse (@var{sx}, @var{sy}, @var{sz}, @var{l})
% Calculate diffuse reflection strength of a surface defined by the normal
% vector elements @var{sx}, @var{sy}, @var{sz}.
% The light vector can be specified using parameter @var{L}. It can be
% given as 2-element vector [azimuth, elevation] in degrees or as 3-element
% vector [lx, ly, lz].
% @seealso{specular, surfl}
% @end deftypefn