MATLAB与拉格朗日插值

我的代码如下:
function yy=lagrange(x1,y1,xx);
x1=(0.4,0.55,0.65,0.8,0.9,1.05);
y1=(0.41075,0.57815,0.69675,0.90,1.00,1.25382);
xx=(0.596,0.99);
n=length(x1)'
l=ones(1,n);
for k=1:n
for j=1:n
if j~=k
l(k)=l(k).*(xx-x1(j))./(x1(k)-x1(j));
end
end
end
sums(y1.*l);
但是我的错了，运行不出来