[MATLAB数学相关] 有个三次样条插值的程序不知道为何，误差有点大

[fanxiangn]

中间追赶法的程序
unction [x,L,U] = zhuigan_Y(A,g)
% A:系数矩阵
% g：等号右端的向量
aerfa(1)=A(1,1); %产生追赶法的L，U矩阵
gama=diag(A,-1);
c=diag(A,1);
n=size(A,1);
beita=zeros(1,n-1);
for i=1:n-1
beita(i)=c(i)/aerfa(i);
aerfa(i+1)=A(i+1,i+1)-gama(i)*beita(i);
end
L=diag(aerfa)+diag(gama,-1);
U=eye(n,n)+diag(beita,1);
y=zeros(1,n);
y(1)=g(1)/A(1,1);
for i=2:n
y(i)=(g(i)-gama(i-1)*y(i-1))/(A(i,i)-gama(i-1)*beita(i-1));
end
x(n)=y(n);
for j=n-1:-1:1
x(j)=y(j)-beita(j)*x(j+1);
end
end