% --------------------------------------------------------------------
%
% Evaluates the first partial derivatives of the bilinear b.f.
% at point 'k' from array 'Gauss_point'
% 'Gauss_point' contains the coordinates of the
%  reference triangle (0,0),(1,0),(0,1)
%
% Presummed ordering of the nodepoints in the reference f.e.:
%     3
%     |\           DER = [ dfi_i/dksi; dfi_i/deta]
%     | \          DER(2x3)
%     |  \
%    1|___\ 2
%
% --------------------------------------------------------------------


function [DER]=shape_der_trian %

      DER(1,1) = -1.0e0;
      DER(2,1) = -1.0e0;

      DER(1,2) =  1.0e0;
      DER(2,2) =  0.0e0;

      DER(1,3) =  0.0e0;
      DER(2,3) =  1.0e0;

return