L = linspace(0,2.*pi,9); xv = 1.2*cos(L)';yv = 1.2*sin(L)';

xv = [xv ; xv(1)]; yv = [yv ; yv(1)];

A = polyarea(xv,yv);

plot(xv,yv); title(['Area = ' num2str(A)]); axis image

figure

dt = DelaunayTri(xv,yv)

triplot(dt);

vxlabels = arrayfun(@(n) {sprintf('P%d', n)}, (1:10)');

Hpl = text(xv, yv, vxlabels, 'FontWeight', 'bold', 'HorizontalAlignment',...

          'center', 'BackgroundColor', 'none');

ic = incenters(dt);

numtri = size(dt,1);

trilabels = arrayfun(@(x) {sprintf('T%d', x)}, (1:numtri)');

Htl = text(ic(:,1), ic(:,2), trilabels, 'FontWeight', 'bold', ...

     'HorizontalAlignment', 'center', 'Color', 'blue');

hold off

[k,a] = convhull(xv,yv)

dt =

 DelaunayTri

 Properties:

     Constraints: []

               X: [9x2 double]

   Triangulation: [7x3 double]

 Methods, Superclasses

k =

    1

    2

    3

    4

    5

    6

    7

    8

    9

    1

面积为

a =

   4.0729