Angles regression is different in the paper and the code!

[tfygg]

In the paper, angles regression is used by equation (6c), I find the tan() is used! While sin() is used in the code!

Why? And which way is the best?

[keck91]

Where did you find this in the code?

[tjmannn]

yeah, I found this too, still confused, tan() seems to have some bugs when angle deviation equals to 90