Why is logic of ArcFace in the losses.py file different from the research paper?

[suryakiran1006]

In the forward function, we have the following logic -

if self.easy_margin:
  final_target_logit = torch.where(target_logit > 0, cos_theta_m, target_logit)
else:
  final_target_logit = torch.where(target_logit > self.theta, cos_theta_m, target_logit - self.sinmm)

From what I understand, this logic is meant to calculate the final_target_logit that is used to compute the loss function. I have two questions here -

1. Why was this conditional statement added in the code when there is no mention of this logic in the research paper.
2. What is the logic behind calculating self.sinmm and self.theta