matlab用jacobi迭代法求解线性方程组出错，有代码..

首先编写M文件
functiom [y,n]=jacobi(A,b,x0,eps)
if nargin==3
eps=1.0e-6;
elseif nargin<3
error
return
end
D=diag(diag(A));
L=-tril(A,-1);
U=-triu(A,1);
B=D\(L+D);
f=D\b;
y=B*x0+f;
n=1;
while norm(y-x0)>=eps
x0=y;
y=B*x0+f;
n=n+1;
end
点击运行出现
??? Error using ==> error
Not enough input arguments.
Error in ==> Untitled2 at 5
error