Why is the variable `nbins` in `_compute_amax_entropy` determined by the sign?

As I understand, HistogramCalibrator collects data distribution of each activation, and it is compressed into 2^bits bins for computing entropy.

In the signed 8-bit setting, integer values among -128~127 can be used, and the number of candidate integers is 256.

In the unsigned 8-bit setting, integer values among 0~255 can be used, and the number of candidate integers is also 256.

So, I think nbins in _compute_amax_entropy should always be 256 regardless of the sign.

However, the implementation in pytorch_quantization, nbins of signed 8-bit setting is half that of unsigned 8-bit setting.

Can you inform me what I missed?

Hi @dk.hong ,

Apologies for the delay,

Did you check the available doc?
Thanks