function [G] = Q4_G(kesi,yita)
%Q4_G 计算G矩阵
%   输入形函数的两个偏导值
%   输出单元G矩阵*(1/4)
G=[ yita-1,     0, 1-yita,      0,yita+1,     0,-yita-1,      0;
    kesi-1,     0,-kesi-1,      0,kesi+1,     0, 1-kesi,      0;
         0,yita-1,      0, 1-yita,     0,yita+1,      0,-yita-1;
         0,kesi-1,      0,-kesi-1,     0,kesi+1,      0, 1-kesi];
G=G/4;
end