'''
function gets(filename)
global x;
global y;
%global len;
[~,~, raw] = xlsread(filename);
len = length(raw);
x = cell2mat(raw(2:len,1));%第一列数据
y = cell2mat(raw(2:len,2));%第二列数据
len = len-1;
lengt = len; %从读取数据来的数据数目
clear p;
p.x = zeros(lengt,1); % 初始化结构体等
p.y = zeros(lengt,1);
s = 0;
for count =1:lengt %将数据赋值到P点
p(count).x = x(count);
p(count).y = y(count);
end
for count2 = 1 :lengt-1
s = s +getcha(p(count2),p(count2+1));
end
s =s + getcha(p(lengt),p(1));
s = 0.5 * abs(s)
function cha = getcha(p1,p2)
cha =p1.x * p2.y - p2.x * p1.y;
'''
