DGF
Interval
-1  -1       % first corner 
 1  1        % second corner
 4  4        % 4 cells in x and 4 in y direction
#
Vertex       % some additional points
 0.75 0.75   % inside the interval
 0.9 0.9     % also inside the interval
 1.25 1.25   % and one outside of the interval
#
Simplexgenerator
display 0    % show result using Triangle viewer

% to use Triangle from a certain path, uncomment path line 
%path $HOME/bin   % path to Triangle

#
BOUNDARYDOMAIN
default 1    % all boundaries have id 1
#BOUNDARYDOMAIN
# examplegrid2a.dgf
