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Align cuTile Gaussian width derivatives with the analytic model - #88

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tpn merged 1 commit into
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codex/release-cutile-widths-20260930
Oct 1, 2026
Merged

tpn merged 1 commit into
mainfrom
codex/release-cutile-widths-20260930

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@tpn

@tpn tpn commented Oct 1, 2026

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Why this is needed

At extreme positive Gaussian widths, cuTile can report a different convergence status or take a different fit step from the analytic CuPy path. Form the physical-width derivatives before combining image planes and applying the log-width chain rule, preserving the model's overflow and underflow behavior.

This extracts the existing arithmetic correction from #83 so it can be reviewed independently for 0.1.3. The observed discrepancy concerns backend consistency; it does not establish incorrect ordinary fits or falsely valid covariance.

Validation

  • Eight regressions covering tiny/huge widths, both width axes, and FP32/FP64 fail on main and pass with this change.
  • All 18 selected cuTile GPU cases passed without skips on RTX PRO 6000 Blackwell, including existing normal-range, weighting, rank, and evaluation-budget checks.
  • CPU suite: 2,783 passed, 209 expected optional/GPU/data skips.
  • make ci-lint passed, including all-files hooks, type checking, and lock validation.

Form physical-width derivatives before combining image planes and
applying the log-width chain rule. This preserves the analytic
model's overflow and underflow behavior for extreme finite widths.

Cover convergence and fit-step parity for both width axes in
single and double precision.

Signed-off-by: Trent Nelson <trentn@nvidia.com>
@tpn
tpn requested a review from melo-gonzo as a code owner October 1, 2026 01:22
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@melo-gonzo melo-gonzo left a comment

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LGTM. The derivative and chain-rule order match the analytic model. All 18 selected cuTile tests passed on RTX 6000 Ada, and all eight new regressions failed on the base revision. Focused CPU suites passed 74 tests with 31 GPU-dependent skips; lint and formatting passed.

@tpn
tpn merged commit 2effbc1 into main Oct 1, 2026
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2 participants