sillt.m

iccg不完全乔尔斯基分解共轭梯度求解大规模稀疏方程组

function sillt(n,aa,nd,nc)
nnd=6;
nnc=10;
for ii=1:n
    if(ii==1)
        mi=1;
    end
    if(ii>1)
        mi=nd(ii-1)+1;
    end
    ni=nd(ii);
    m1=ni-1;
    for kk=mi:m1
        if(mi>m1)
            continue
        end
        ns=nc(kk);
        kka=nd(ns);
        if(abs(aa(kka)<1.0e-20))
            '分母为零，请检查原系数矩阵对角线元素' 
            '行号I=',ii
 %           stop 1111
        end
        ca=aa(kk)/aa(kka);
        k1=kk+1;
        for jj=k1:ni
            nb=nc(jj);
            n2=nd(nb-1)+1;
            if(nc(n2)>ns)
                continue
            end
            m2=nd(nb);
            for l=n2:m2
                if(nc(l)~=ns)
                    continue
                end
                aa(jj)=aa(jj)-ca*aa(l);
            end
            continue
        end
    end
    cb=abs(aa(ni));
    if(cb>1.0e-20)
        continue
    end
    for j1=mi:m1
        cb=cb+abs(aa(j1));
    end
    aa(ni)=cb;
end