intgausslager.m

高斯-拉盖尔公式的MATLAB代码。。。。。。。。。。

function q=IntGaussLager(f,n,AK,XK)
%被积函数：f;
%所采用的积分点个数:n;
%自定义系数:AK;
%自定义积分点:XK;
%积分值:q;
if(n<6 && nargin == 2)
    AK=0;
    XK=0;
else
    q=sum(AK.*subs(sym(f),findsym(f),XK));
end
switch n
    case 2,       %n=2时，采用表中对应的系数进行计算
        q=0.853553*subs(sym(f),findsym(sym(f)),-0.585786)+...
        0.146447*subs(sym(f),findsym(sym(f)),3.414214);
    case 3,       %n=3时，采用表中对应的系数进行计算
        q=0.711093*subs(sym(f),findsym(sym(f)),0.415575)+...
        0.278518*subs(sym(f),findsym(sym(f)),2.294280)+...
       0.0103893*subs(sym(f),findsym(sym(f)),6.289945);
    case 4,       %n=4时，采用表中对应的系数进行计算
        q=0.603154*subs(sym(f),findsym(sym(f)),0.322548)+...
        0.357419*subs(sym(f),findsym(sym(f)),1.745761)+...
        0.0388879*subs(sym(f),findsym(sym(f)),4.536620)+...
        0.000539295*subs(sym(f),findsym(sym(f)),9.395071);
    case 5,       %n=5时，采用表中对应的系数进行计算 
        q=0.521756*subs(sym(f),findsym(sym(f)),0.263560)+...
        0.398667*subs(sym(f),findsym(sym(f)),1.413403)+...
        0.0759424*subs(sym(f),findsym(sym(f)),3.596426)+...
        0.00361176*subs(sym(f),findsym(sym(f)),7.085810)+...
        0.0000233700*subs(sym(f),findsym(sym(f)),12.640801);
end