Doubts about implementation of carlini_wagner attack

[chinmay5]

Thank you so much for the wonderful library. I have one doubt about carlini_wagner attack though. The original paper talks about using 1/2 * (tanh (w) + 1) in order to ensure the delta values lie between 0 and 1. It seems here the code uses tanh only to ensure rescaling but the optimization is still done on the values of x and x + delta . In that case, why are we doing an extra clipping here? If tanh is only used to ensure values remain within the range, can we use a normal torch.clamp() function instead? Is there some reason to still use the tanh() function then?

I am a bit confused about the implementation and some pointers would be really appreciated.