Request:

We propose allowing contributions of float values (including negative ones) to contributeToHistogramOnEvent with a sensitivity of 2^16.

Background:

Currently, contributions are limited to integer values up to the L1 bound of 2^16. For specific use cases such as encoding gradients (for noised gradient descent methods), we need to encode decimal values that can be negative. The current implementation requires positive and negative integers values to be contributed separately into two different buckets, which doubles the privacy cost. Since the Laplace distribution considers the L1 norm (the sum of absolute values), the limitation to non-negative integers is unnecessary from a differential privacy perspective.