介绍简化的再生核方法。令
fi(x)=LxiR(x,xi),i=1,2,…,n,
g1(x)=R(x,a),g1(x)=R(x,b)
由再生核性质知:f1(x),f2(x),…,fn(x),g1(x),g2(x)线性无关。
令Sn=span{f1(x),f2(x),…,fn(x),g1(x),g2(x)},Pn:W32[a,b]→Sn为正交投影算子,则f1(x),f2(x)…fn(x),g1(x),g2(x)为Sn的一组基。
由泛函的相关定理,假设ui(x)是(7)的解,则Pnui是(7)的逼近解。由uin■Pnui∈Sn,故Vn可设为
uin=ai1f1+ai2f2+…+ainfn+bi1g1+bi2g2 (8)
定理2.1:设ui是(7)的解,则Pnui满足:
〈uin,fj〉=h(xj),j=1,2,…,n〈uin,g1〉=■〈uin,g2〉=■ (9)
证明:定理2.2在[a,b]上,uin一致收敛于ui。
接下来确定未知系数ai1,ai2,…ain,bi1,bi2。将式(8)代入式(9),得到线性方程组:
■aij〈fj,fi〉+bij〈fj,g1〉+bi2〈fj,g2〉=h(xi),i=1,2,…,n■aij〈fj,g1〉+bi1〈g1,g1〉+bi2〈g1,g2〉=■■aij〈fj,g1〉+bi1〈g2,g1〉+bi2〈g2,g2〉=■
可得
(ai1,ai2,…,ain,bi1,bi2)r=M-1bi,i=0,1,2,…,m。
进而得到ui近似解。故而,我们得到式(1)的近似解.
Um,n=■uin
三、结论
通过之前的理论分析可知,同伦渐进和简化的再生核方法成功地解决了非线性方程的问题。
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