% --------------------------------------------------------------------
% Evaluates the trilinear b.f. at point 'k' from array 'points'
% 'points' contains the coordinates of the reference triangle
% (0,0),(1,0),(0,1)
%
% Presummed ordering of the nodepoints in the reference f.e.:
%
%     3
%     |\           
%     | \          FUN(3)
%     |  \
%    1|___\ 2
%
% --------------------------------------------------------------------


function [BF]=shape_fun_trian(Gauss_point,k)

      ksi  = Gauss_point(1,k);
      eta  = Gauss_point(2,k);

      BF(1) = 1.0e0 - ksi - eta;
      BF(2) = ksi;
      BF(3) = eta;

return