Si2:Aula2

N =10;
x1=-2;  x2= 2;
y1=-2;  y2= 2;

for i=1:N
  for j=1:N
    r = (i-1)/(N-1);
    s = (j-1)/(N-1);    
    x(i,j)=x1 *r + x2*(1-r);
    y(i,j)=y1 *s + y2*(1-s);

    xv(i) =x(i,j);
    yv(j) =y(i,j);
    z(i,j)=1-x(i,j)-y(i,j);
  end
end

surf(x,y, z,'facecol','interp')  

fig = gcf();
fig.color_map=coolcolormap(32);
contour2d( xv,yv, z,20)