张德丰matlab数值分析源码

function I = IntGauss(f,a,b,n,AK,XK) if(n<5 && nargin == 4) AK = 0; XK = 0; else XK1=((b-a)/2)*XK+((a+b)/2); I=((b-a)/2)*sum(AK.*subs(sym(f),findsym(f),XK1)); end ta = (b-a)/2; tb = (a+b)/2; switch n case 0, I=2*ta*subs(sym(f),findsym(sym(f)),tb); case 1, I=ta*(subs(sym(f),findsym(sym(f)),ta*0.5773503+tb)+... subs(sym(f),findsym(sym(f)),-ta*0.5773503+tb)); case 2, I=ta*(0.55555556*subs(sym(f),findsym(sym(f)),ta*0.7745967+tb)+... 0.55555556*subs(sym(f),findsym(sym(f)),-ta*0.7745967+tb)+... 0.88888889*subs(sym(f),findsym(sym(f)),tb)); case 3, I=ta*(0.3478548*subs(sym(f),findsym(sym(f)),ta*0.8611363+tb)+... 0.3478548*subs(sym(f),findsym(sym(f)),-ta*0.8611363+tb)+... 0.6521452*subs(sym(f),findsym(sym(f)),ta*0.3398810+tb)... +0.6521452*subs(sym(f),findsym(sym(f)),-ta*0.3398810+tb)); case 4, I=ta*(0.2369269*subs(sym(f),findsym(sym(f)),ta*0.9061793+tb)+... 0.2369269*subs(sym(f),findsym(sym(f)),-ta*0.9061793+tb)+... 0.4786287*subs(sym(f),findsym(sym(f)),ta*0.5384693+tb)... +0.4786287*subs(sym(f),findsym(sym(f)),-ta*0.5384693+tb)+... 0.5688889*subs(sym(f),findsym(sym(f)),tb)); end