function sina(n,aa,f,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
    m1=nd(ii)-1;
    for k=mi:m1
        if(mi>m1)
            continue
        end
        ns=nc(k);
        kka=nd(ns);
        ca=aa(k)/aa(kka);
        f(ii)=f(ii)-ca*f(ns);
    end
end
for i2=1:n
    ii=n-i2+1;
    if(ii==1)
        mi=1;
    end
    if(ii>1)
        mi=nd(ii-1)+1;
    end
    ni=nd(ii);
    m1=ni-1;
    f(ii)=f(ii)/aa(ni);
    mi
    for k=mi:m1
        if(mi>m1)
            continue
        end
        ns=nc(k);
        f(ns)=f(ns)-aa(k)*f(ii);
    end
end