Commit Graph
6 Commits
Author SHA1 Message Date
logaritmiskandClaude Opus 5 e4d6dc4028 fix: warn on dropped builders and values; stop exporting EP internals
`h.event(1).team(["x"]).team(["y"]).ranking([0, 1]);` without the
terminal `.commit()` was a silent no-op: no warning, no error, and the
next thing the caller does is converge an empty history and read `None`
skills. `EventBuilder` already carried a `#[must_use]`; the value types
around it did not, so the same silence covered `Team::with_members`,
`Member::new`, `Outcome::*`, `Joint` and `Prediction::outcomes`.

`#[must_use]` now goes on the *types* rather than being sprinkled over
methods, which covers every constructor and builder setter at once and
gives the crate a rule where it previously had a list. Verified by
compiling a program that drops each one and reading the warnings back,
rather than by assuming the attribute took.

Visibility, from #73: `Gaussian::damp_natural` was reachable from
outside the crate despite being an EP damping internal called only from
`src/factor/`. The stray `pub fn`s inside the private `time_slice`,
`key_table` and `matrix` modules are now `pub(crate)`, so their
visibility states what it means instead of relying on the module being
private.

`storage/mod.rs` and `factor/mod.rs` become `storage.rs` and
`factor.rs`.

Closes #67. Refs #73.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
2026-09-09 21:24:37 +02:00
logaritmiskandClaude Opus 5 a0c2f78aed feat: add the missing trait impls and make #[must_use] consistent
Trait coverage (#76), all additive:

  History          Debug is still absent - see below
  HistoryBuilder   + Debug   (it derived Clone but not Debug)
  Rating           + PartialEq  (Gaussian had it; Rating is a Gaussian
                                 plus three scalars and had none)
  Event/Team/Member + PartialEq (input value types with no way to compare
                                 them, which made round-trip tests awkward)
  ConvergenceReport + PartialEq

`#[must_use]` (#67). The coverage had no rule: `filtered_log_evidence`
had it and `log_evidence` did not; `rating` had it and `current_skill`
did not; `Rating::with_drift_scale` had it and `Member::with_drift_scale`
did not.

Now on the types — `EventBuilder`, `HistoryBuilder`, `Prediction`,
`Gaussian`, `OwnedGame` — which covers most method returns at once, plus
the `History` accessors individually.

`EventBuilder` gets a message, because a dropped builder is the worst
case in the set: measured, `h.event(1).team(["x"]).team(["y"]).winner(0)`
without `.commit()` leaves `time_slices_len() == 0` and every skill
`None`, with no warning at all.

And `ConvergenceReport`'s `#[must_use]` moves off the TYPE onto
`converge_partial`, where its stated reason is true. It read "from
`converge_partial` this may describe a fit that stopped at max_iter" but
fired on `converge` too — where that is false, since `converge` returns
`Err(NotConverged)` in exactly that case. So the crate's own front-page
example warned, and every quickstart had to write `let _ =`. Verified
from a consumer crate: `h.converge()?;` now compiles clean.

Marking the types made eight method-level attributes redundant, which
clippy's `double_must_use` caught — that is the type-level marker doing
its job, and the eight are removed.

Refs #76, #67

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
2026-09-09 20:38:39 +02:00
logaritmiskandClaude Opus 5 bbc7705c75 fix!: report an unresolvable prediction grid instead of clamping
`grid_shape` asked for 12 nodes across the narrowest feature and then
clamped to MAX_GRID_POINTS with no detection that the request was not
met. Past `step/sigma ~ 1.7` the trapezoid rule stops resolving the
density, and the result is unbounded:

  sigma_a   step/sig_a   P(a first)   exact      total
  2.0e-3      0.86       0.515953    0.515953   1.000000
  1.0e-3      1.72       0.517185    0.515953   1.002388
  1.0e-4     17.17       2.791336    0.515953   5.410065

A probability of 2.79. Reachable through `predict_outcome` with a pinned
reference competitor — a documented pattern — where `predict_outcome` and
`predict_win_probabilities` disagreed 44x and `predict_outcome` was the
wrong one.

There is no useful answer on the far side of that cliff, so this reports
`GridTooCoarse` rather than guessing, and the message points at
`predict_win_probabilities`, which answers the same matchup through
adaptive quadrature and is accurate there to 1e-13. The floor is 4 nodes
per feature rather than the 12 requested, because the request carries
margin: measured accurate to 2.2e-12 at 1.4 nodes per sigma and wrong by
1.2e-3 at 0.7.

This also fixes the `ln k` ceiling violation. `expected_information_gain`
weights `probability * divergence`, so probabilities of 3.97 and 2.62
made it return 3.237828 nats against `ln 2 = 0.693147` — 4.67x over. The
crate's docs call that ceiling its sharpest test and record a prototype
once returning 4.77 nats; it was live again by a different route.

The new sweep then caught a second, independent defect: `kl_divergence`
returned NEGATIVE values, worst -5.55e-17, exactly one ULP of its
`- 1.0`. Rewritten as `0.5*(u - ln1p(u)) + gap^2/(2*var_p)` with
`u = var_q/var_p - 1`, so both terms are non-negative by construction.
It is also more accurate where it matters: at `u = 1e-9` the old form
returned 0.0 where the true value is 2.5e-19, and well-conditioned cases
are unchanged.

tests/prediction_bounds.rs sweeps rather than spot-checks, because a
single fixture cannot defend a bound like this — the previous check
passed throughout. It asserts the sweep still reaches the coarse-grid
regime, so it cannot quietly stop testing the case it was written for.

BREAKING CHANGE: `predict_outcome`, `predict_ranking` and
`expected_information_gain` return `GridTooCoarse` for matchups whose
performance sigmas are too far apart to integrate on one grid. They
previously returned wrong answers, including probabilities above 1.

Closes #55, closes #56

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
2026-09-09 17:21:00 +02:00
logaritmiskandClaude Opus 5 17d072b2ae fix: route every transcendental through libm, and combine sigmas with hypot
Follow-on from #41, which added `libm` for `erfc`. Surveying what else
the dependency offers: its unique surface over `std` is `erf`/`erfc`,
`lgamma`/`tgamma` and Bessel functions, and only the first was ever
needed. But the survey found something better than another special
function.

`std`'s `exp` and `ln` delegate to the *system* math library. IEEE 754
specifies the basic operations and `sqrt` exactly and says nothing about
transcendentals, so those differ per platform. Measured here over 200k
inputs:

    exp: 19425/200000 differ from libm (worst 1 ulp)
    log:  9932/200000 differ

Inference is an iterative fixed point, so a one-ULP difference can change
an iteration count and move the answer by more than one ULP. Routing
every transcendental through `libm` makes a fit reproducible across
platforms — a stronger guarantee than `tests/determinism.rs`, which only
covers thread counts.

It costs nothing. `Batch::iteration` measured -2.7% [-5.7%, -0.3%] with
the whole set swapped, and not one golden moved.

Also switches the two places that combined sigmas as
`sqrt(a^2 + b^2)` to `hypot`. Squaring overflows to infinity above
~1.3e154 and flushes to zero below ~1.5e-154 — measured, the naive form
returns `inf` where `hypot` returns 1.41e160 — and `Gaussian`'s
constructors are public, so a caller can reach both ends.

Deliberately not done: rewriting the KL divergence's `ln` of a ratio via
`ln_1p`. The cancellation is real as the ratio approaches one, but
measured absolute error is at most ~1e-11 in a quantity of order 0.4
nats, so it changes nothing.

The invariant is recorded in `CLAUDE.md` and on `erfc`'s own docs, since
nothing enforces it mechanically.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
2026-09-07 22:33:30 +02:00
logaritmiskandClaude Opus 5 3dd659307a fix: replace the erfc approximation with libm, for free
#41 asked whether the Numerical Recipes `erfcc` approximation — 1.2e-7
relative, and the binding accuracy constraint on the whole crate — was
worth replacing, given it sits in the inference hot loop. It is, and it
costs nothing.

Measured, against an independent incomplete-gamma reference:

    range        previous (NR)        libm
    [-3, 0]            7.95e-8     2.15e-14
    [0, 0.5]           8.69e-8     4.70e-14
    [0.5, 2]           9.38e-8     1.24e-12
    [2, 6]             1.04e-7     5.20e-14
    [6, 26]            1.07e-7     1.75e-13

    erfc(0)          1.00000003          1.0  (exactly)
    |erfc(z)+erfc(-z)-2|  6.00e-8     2.22e-16

Performance, on `benches/batch.rs`: change [-3.34% +2.26%], p = 0.89 —
no change detected.

That result is counterintuitive, because libm's erfc is 1.65x slower
when swept uniformly over [-2.5, 2.5]. The sweep was the wrong input
distribution. Capturing the arguments inference actually passes:

    |x|<0.5    96.16%
    0.5-0.84    2.05%
    0.84-1.25   1.24%
    1.25-2      0.54%
    2-6         0.00%

98% fall below 0.84375, which is exactly where FDLIBM skips the
exponential entirely — while the NR form always pays for one. On the
real trace libm is the faster of the two (3.23 vs 3.78 ns/call).

An ad-hoc `Instant` harness reported a 16% end-to-end speedup; that was
an artifact of its own setup allocating and leaking per run, and
criterion's verdict of "no change" is the one to believe.

What it bought:

- `compute_margin` against exact quantiles: 8.4e-8 -> 1.7e-16.
- `cdf(mu, mu, sigma)` is now exactly 0.5; it was 1.5e-8 out.
- `sf + cdf` sums to one within a ULP, from 3e-8.
- `erfcx`'s two branches now agree to round-off across the crossover
  rather than to 1e-7, so the log-space evidence path and the linear one
  are consistent.
- Ten test tolerances tightened from 1e-6 to 1e-13..1e-15, and the
  prediction floor is now the integrator's rather than `cdf`'s.

Five goldens moved, by 2.4e-9 to 6e-7 — the magnitude of the removed
error, and `test_env_ttt`'s mu still rounds to the same six decimals.
Re-recorded with more digits so future drift stays visible. Verified as
movement toward truth per the goldens policy: every value now derives
from a primitive checked against an independent reference and satisfying
the exact identities, which the previous one did not.

Adds `libm` — zero transitive dependencies, rust-lang maintained.

Closes #41

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
2026-09-07 22:25:00 +02:00
logaritmiskandClaude Opus 5 bb2a845882 feat!: N-team outcome prediction with draw mass, replacing the 2-team panic
`predict_outcome` asserted `teams.len() == 2` and returned `[p, 1 - p]`,
allocating no probability to a draw even with `p_draw > 0`. For a
draw-enabled model the numbers were simply wrong, at any team count.

It now returns `Result<Prediction, InferenceError>` and supports N teams.

Two algorithms, both deterministic:

- Who finishes first. Performances are independent Gaussians, so this
  separates into a one-dimensional integral per team rather than a
  multivariate orthant probability. Adaptive Gauss-Kronrod evaluates it
  to ~1e-15, matching the exact two-team closed form.
- A specific finishing order. The factor graph only constrains
  rank-adjacent teams, so a full order is a chain of local constraints,
  not a general orthant integral. That chain collapses into a sequential
  recursion over cumulative integrals: O(teams * grid) per order.

Fixed-node Gauss-Hermite is the obvious tool for the first and is a trap:
when a rival's sigma is small the CDF product becomes a step narrower
than the node spacing, and the nodes step over it. Measured 4.4e-4 off
the closed form on a mildly skewed matchup and 1.7e-2 on a small-sigma
one, while still returning something that looks like a probability.
Adaptive refinement is what makes that case safe, and
`win_probabilities_survive_a_rival_with_a_tiny_sigma` pins it down.

The acceptance test is an identity rather than a golden: the outcome
space is exhaustive and disjoint, so the probabilities sum to one. Any
drift is integration error and nothing else. Gauss-Hermite failed it at
4.4e-4; this holds to ~1e-9.

Also from #21: unknown keys are now reported rather than dropped, so a
team of strangers can no longer produce a confident-looking prediction.
`predict_quality` returns `Result` for the same reason.

BREAKING CHANGE: `predict_outcome` returns `Result<Prediction, _>`
instead of `Vec<f64>`; `predict_quality` returns `Result<f64, _>`.

Refs #21, #39

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
2026-09-07 14:55:11 +02:00