tensorflow / tensorflow/probability

RelaxedOneHotCategorical has incorrect output for logits under 1 when logits are type of float32

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Description

Hi, I was trying out the RelaxedOneHotCategorical function on tensorfloa_probability version 0.19.0. The following code gives me the incorrect distribution.

from tensorflow_probability.substrates import jax as tfp
temperature = 0.5
p = [0.1, 0.5, 0.4]
dist = tfp.distributions.RelaxedOneHotCategorical(temperature, logits=p)
from jax import random
dist.sample(seed=random.PRNGkey(0))

The expected behavior is "the 2nd class is the most likely be the largest component in samples". However, I got the reverse probability instead.

Array([0.9872344, 0.00204739, 0.01071812], dtype=float32)

This behavior disappears when the logits are > 1, or if we cast p to be float16.

Is this expected?

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Research direction

Start with the provided Python reproducer for tfp.distributions.RelaxedOneHotCategorical using the JAX substrate and float32 logits. Inspect the RelaxedOneHotCategorical sampling entry point and compare float32 behavior with the float16 and logits-greater-than-one cases; done means the reported output is explained or corrected and the expected class probabilities are preserved.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
machine-learning
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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