fix: safe negative-RT handling and JAX backend for RDM3#926
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AlexanderFengler merged 3 commits intomainfrom Mar 12, 2026
Merged
fix: safe negative-RT handling and JAX backend for RDM3#926AlexanderFengler merged 3 commits intomainfrom
AlexanderFengler merged 3 commits intomainfrom
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- Replace element-wise jax_check_parameters for rt > 0 with jnp.where + LOGP_LB floor in logp_rdm3. This clamps negative decision times to a small epsilon before passing to the PDF/CDF, preventing NaN in the likelihood and providing a finite gradient floor per trial. - Set backend to "jax" and add default HalfNormal priors for A and t in both racing_diffusion_3_config and rdm3_config. Made-with: Cursor
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Pull request overview
This PR improves numerical stability and JAX integration for the 3-choice Racing Diffusion Model (RDM3) analytical likelihood, aiming to prevent NaNs when non-decision time exceeds observed RT and to provide sensible defaults for inference.
Changes:
- Clamp negative decision times inside
logp_rdm3and floor affected trials toLOGP_LBto avoid NaNs in the likelihood. - Set the RDM3 analytical likelihood backend to
"jax"in the default model configs. - Add default HalfNormal priors for
Aandtin both RDM3-related configs.
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.
| File | Description |
|---|---|
src/hssm/modelconfig/rdm3_config.py |
Switch analytical backend to JAX and add default priors for A and t. |
src/hssm/modelconfig/racing_diffusion_3_config.py |
Same as above for the racing_diffusion_3 model config. |
src/hssm/likelihoods/analytical.py |
Make RDM3 logp robust to rt - t <= 0 via safe clamping and LOGP_LB flooring. |
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This file is dead code — the dynamic config loader in modelconfig/__init__.py derives module names from the model name "racing_diffusion_3", so only racing_diffusion_3_config.py is ever loaded. rdm3_config.py was never imported or called. Made-with: Cursor
cpaniaguam
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Mar 10, 2026
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cpaniaguam
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lgtm. Just one little suggestion.
Pass logp_rdm3 epsilon through JAX RDM internals to keep clamping behavior consistent and preserve LOGP_LB dtype under JAX. Add a regression test ensuring rt<=t returns LOGP_LB and stays finite for RDM3. Made-with: Cursor
AlexanderFengler
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Mar 12, 2026
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lgtm,thanks @krishnbera
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Made-with: Cursor