ParticleFilter SLAM code error

[yimengweima0]

Hi，
I am studying ParticleFilter SLAM. When I run the ParticleFilter code which is " pf.run(100)" in matlab， I find a error. The error is as follows :
The assignment cannot be performed because the size on the left is 1000 × 1. The size on the right is 999 × 1.
error : ParticleFilter/predict (line 414):
pf.x(:,3) = angdiff(pf.x(:,3));
I would appreciate it if you could fix the code.
Thanks very much!