Equation field guide
Zero-point Z
The zero-point is the integer code chosen to mean the real value zero.
Why subtract Z?
If Z = 10, the code q = 10 gives r = S(10 − 10) = 0. Codes below 10 decode to negative values and codes above 10 decode to positive values when S is positive.
Subtracting Z recenters the code system around real zero. The code range can then be shifted to better cover an asymmetric range of model values.
Why exact zero matters
Neural-network operations often use zero directly, for example padding an image boundary with zeros or replacing negative activations with zero in a ReLU operation. An integer code for exact zero helps these operations retain their intended meaning after quantization.
Z is an integer parameter of the representation, not the same thing as the model value r.