function quad=GLintegration(f)
% Gauss-Lengendre 求積公式
%輸入f是被積函數的字符表達式

%輸出－－quad是積分值
A=[0.9061798,0.5384693,0,-0.5384693,-0.9061798];% A是1XN的Gauss-Lengendre節點坐標
W=[0.2369239,0.4786286,0.5688889,0.4786286,0.2369239];% W是1XN的Gauss-Lengendre節點對應的權值
a=-1;
b=1;
N=length(A);
T=zeros(1,N);
T=((a+b)/2)+((b-a)/2)*A;
quad=((b-a)/2)*sum(W.*feval(f,T));