logarithmic space mode: pure_root gains space='x'|'log' (default reproduces the published grid bit-for-bit), u = sign(x-c)*log1p(|x-c|/xtol) with c = the end of smaller |f| and s = xtol fixed by derivation; gates G1/G2' pinned by tests/test_log_space.py (7 green); sweep writes the log grid to its OWN sweep_log.json so the verified sweep_full.json is untouched
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
This commit is contained in:
@@ -47,6 +47,39 @@
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Не прошёл G2 → закрывается: широкие скобки куплены ценой канонического набора, а это трейд, на котором
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провалились все прежние попытки.
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## 3a. ПОПРАВКА 1 (2026-09-20, решение Валерия: вариант B)
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**Что произошло:** строгий G2 («шаг в `u` совпадает со шагом в `x` до 1e-12») провален **выводом**, без
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прогона, и не для одного кандидата, а для всех доступных беспараметрических единиц — марш требует
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ОТНОШЕНИЯ расстояний, тождественность требует АБСОЛЮТНОЙ шкалы (разбор в `FINDINGS_logarithmic.md` §1).
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**Решение (Валерий, вариант B):** строгое чтение G2 заменяется его же **измеримым** чтением, которое
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уже стоит в этой пред-регистрации как L2:
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> **G2′:** на APS-154 суммарная цена не растёт; ни одна задача канонического набора не становится
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> дороже по вызовам `f`.
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Это **ослабление** пред-регистрированного критерия после его провала — записано как ослабление, а не
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как «уточнение», и принято решением, а не молча.
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**Единица `s` фиксируется ВЫВОДОМ здесь и не выбирается по рейтингу:**
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> `c` = конец скобки с меньшим |f| (сторона, к которой корень ближе);
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> **`s` = `xtol`**.
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Обоснование, а не удобство: задача преобразования — считать **декады, оставшиеся до различимости**.
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Единственная длина в задаче, говорящая «ниже этого различий нет», — это `xtol`, и она приходит от
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вызывающего наравне с `a`, `b`, `f`, то есть не является нашей константой. При таком выборе `u`
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покрывает ровно `log(w/xtol)` единиц — ту самую величину, в которой сформулирована гарантия метода
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`2⌈log₂(w/xtol)⌉+3`, так что марш становится линейным в мере собственной гарантии. Вырождения нет:
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`xtol > 0` всегда, и `|x−c| = 0` даёт `u = 0`, а не деление на ноль.
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Отвергнутая альтернатива (для протокола): самомасштабируемая `s = |x−c|` вырождается на первом шаге,
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потому что итерат стартует в конце с меньшим |f|, то есть ровно в `c`.
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**Режим требует выведенной шкалы:** `space="log"` допустим только при `scale ∈ {derived, derived3}` —
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в log-пространстве нужен наклон; при прочих шкалах вызов обязан падать, а не считать молча.
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## 4. Цели (записаны в `NEXT_PAPER_logarithmic.md` заранее, не подгонялись)
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| величина | цель | где сейчас |
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+61
-1
@@ -118,6 +118,50 @@ PURE_SIMS = {
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GUARDS = ("none", "bracket", "step", "both", "project", "safe", "credit")
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SPACES = ("x", "log")
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def _log_map(t, c, s):
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"""u = sign(t - c) * log1p(|t - c| / s). An ADDITIVE step in u is a
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MULTIPLICATIVE step in x, which is what the wide-bracket families need: the
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search there must cross up to twelve decades, and an absolute step sized by
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the local slope knows nothing about how many decades remain."""
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d = t - c
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return math.copysign(math.log1p(abs(d) / s), d)
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def _log_unmap(u, c, s):
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return c + math.copysign(s * (math.expm1(abs(u))), u)
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def _log_space_step(S, x, fx, far, slope, c, s):
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"""The same similarity rule, the same derived scale, read in u rather than x.
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dx/du = s + |x - c|, so the slope in u is slope_x * (s + |x - c|); the scale
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is that slope times the distance to the far end IN u, exactly as in x-space.
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Returns the step in x (None when u-space cannot be read).
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`s` is NOT a free unit: PREREG amendment 1 fixes s = xtol by derivation - the
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only length in the problem that says "below this nothing is distinguishable",
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supplied by the caller like a, b and f. With it u spans log(w/xtol) units,
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the very measure the method's own guarantee 2*ceil(log2(w/xtol)) + 3 is
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stated in, so the march is linear in the measure of the guarantee.
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"""
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u_x = _log_map(x, c, s)
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u_far = _log_map(far, c, s)
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du = u_far - u_x
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if du == 0.0 or not math.isfinite(du):
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return None
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slope_u = slope * (s + abs(x - c))
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sc_u = abs(slope_u) * abs(du)
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if sc_u == 0.0 or not math.isfinite(sc_u):
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return None
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u_new = u_x + (1.0 - S(abs(fx) / sc_u)) * du
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x_new = _log_unmap(u_new, c, s)
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if not math.isfinite(x_new):
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return None
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return x_new - x
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class _Safeguard:
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"""Parameter-free worst-case protection. See the module docstring."""
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@@ -369,7 +413,7 @@ def _local_order(x2, f2, x1, f1, x0, f0):
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def pure_root(f, a, b, xtol, maxfev, similarity="ratio", scale="derived",
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guard="step", stats=None, budget_factor=2.0,
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budget_extra=None, endowment=1.0):
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budget_extra=None, endowment=1.0, space="x"):
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"""The pure similarity root finder.
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similarity : key into PURE_SIMS
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@@ -421,6 +465,12 @@ def pure_root(f, a, b, xtol, maxfev, similarity="ratio", scale="derived",
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if scale not in ("derived", "derived3", "derived_rho", "derived3_rho",
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"derived3_m", "start", "bracket"):
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raise ValueError(f"unknown scale {scale!r}")
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if space not in SPACES:
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raise ValueError(f"unknown space {space!r}")
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if space == "log" and scale not in ("derived", "derived3"):
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# u-space needs a slope; with a chosen or bracket scale there is none to
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# transform, and computing something anyway would hide that (PREREG §3a).
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raise ValueError("space='log' requires scale in {'derived', 'derived3'}")
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S = PURE_SIMS[similarity]
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g = Counter(f, maxfev)
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x = 0.5 * (a + b)
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@@ -541,6 +591,16 @@ def pure_root(f, a, b, xtol, maxfev, similarity="ratio", scale="derived",
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if sc == 0.0 or not math.isfinite(sc):
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x_new = 0.5 * (A + B)
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else:
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step = None
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if space == "log":
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# c = the bracket end with the smaller |f| (the side the
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# root is nearer); s = xtol, fixed by derivation in
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# PREREG amendment 1, never chosen. Falls back to the
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# x-space step when u cannot be read, so the mode can
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# only differ where it is defined.
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c_near = A if abs(FA) <= abs(FB) else B
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step = _log_space_step(S, x, fx, far, slope, c_near, xtol)
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if step is None:
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step = (1.0 - S(abs(fx) / sc)) * (far - x)
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if sg.reject_step(step):
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x_new = 0.5 * (A + B)
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+28
-7
@@ -101,20 +101,27 @@ BASELINES = {
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def make_method(spec):
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"""spec is ('base', name) or ('pure', similarity, scale, guard)."""
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"""spec is ('base', name) or ('pure', similarity, scale, guard[, space]).
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The optional 5th element is the SPACE the step is read in (PREREG
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amendment 1, 2026-09-20): omitted or "x" reproduces the published grid
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bit-for-bit, "log" is the logarithmic-march mode."""
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if spec[0] == "base":
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return BASELINES[spec[1]]
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_, sim, scale, guard = spec
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sim, scale, guard = spec[1], spec[2], spec[3]
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space = spec[4] if len(spec) > 4 else "x"
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def m(f, a, b, xtol, maxfev):
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return pure_root(f, a, b, xtol, maxfev, similarity=sim,
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scale=scale, guard=guard)
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scale=scale, guard=guard, space=space)
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return m
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def label(spec):
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if spec[0] == "base":
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return spec[1]
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if len(spec) > 4 and spec[4] != "x":
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return f"{spec[4]}.{spec[1]}.{spec[2]}.{spec[3]}"
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return f"pure.{spec[1]}.{spec[2]}.{spec[3]}"
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@@ -152,6 +159,16 @@ def evaluate(spec):
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return res
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def build_grid_log(smoke):
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"""The logarithmic-space grid (PREREG 2026-09-20). Baselines are NOT recomputed:
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their numbers are already in sweep_full.json and re-running known expensive
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controls is waste. Only the derived scales are admissible in u-space."""
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sims = ["ratio", "cbrt"] if smoke else sorted(PURE_SIMS)
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guards = ("credit", "project") if smoke else GUARD_MODES
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return [("pure", sim, sc, gu, "log")
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for sim in sims for sc in ("derived", "derived3") for gu in guards]
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def build_grid(smoke):
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specs = [("base", nm) for nm in BASELINES]
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sims = sorted(PURE_SIMS)
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@@ -171,10 +188,11 @@ def build_grid(smoke):
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def main():
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smoke = "--smoke" in sys.argv
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specs = build_grid(smoke)
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logmode = "--log" in sys.argv # the u-space grid, written to its OWN file
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specs = build_grid_log(smoke) if logmode else build_grid(smoke)
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t0 = time.time()
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print(f"sweep: {len(specs)} configurations x 199 problems "
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f"({'SMOKE' if smoke else 'FULL'})", flush=True)
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f"({'SMOKE' if smoke else 'FULL'}{', LOG-SPACE' if logmode else ''})", flush=True)
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workers = max(1, min(8, (os.cpu_count() or 2) - 1))
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with Pool(workers) as pool:
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@@ -185,7 +203,10 @@ def main():
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print(f" {i}/{len(specs)} done, "
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f"{time.time() - t0:.0f}s elapsed", flush=True)
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out = "sweep_smoke.json" if smoke else "sweep_full.json"
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# the published sweep_full.json is what verify_article.py checks the paper
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# against, so the log grid never writes into it
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out = ("sweep_log_smoke.json" if smoke else "sweep_log.json") if logmode else \
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("sweep_smoke.json" if smoke else "sweep_full.json")
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with open(out, "w", encoding="utf8") as fh:
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json.dump(results, fh)
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print(f"\nwrote {out} ({time.time() - t0:.0f}s total)\n", flush=True)
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@@ -225,7 +246,7 @@ def report(results, top=20):
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for r in results:
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if r["spec"][0] != "pure":
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continue
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_, sim, sc, gu = r["spec"]
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sim, sc, gu = r["spec"][1], r["spec"][2], r["spec"][3]
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if sc != scale or gu != "step" or sim not in group:
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continue
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cnt += 1
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File diff suppressed because one or more lines are too long
@@ -0,0 +1,107 @@
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"""Gates for the logarithmic space mode — checked BEFORE the ranking is consulted.
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PREREG_logarithmic_2026-09-20.md, amendment 1:
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G1 the transform is parameter-free: c and s come from the bracket and the caller
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(c = the end with the smaller |f|, s = xtol), never from a chosen constant.
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G2' on APS-154 the cost must not grow (measured by the sweep, not here); what IS
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checkable here is that the deviation from the x-space step is of SECOND order
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in the bracket width, i.e. it vanishes as the bracket collapses.
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Also pinned: the transform round-trips, u-space is rejected where it cannot be read
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(no silent fallback to a different scale), and the mode still solves.
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"""
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from __future__ import annotations
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import inspect
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import math
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import re
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import pytest
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from simroot import pure as P
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def _steps(width, space, fun=None):
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"""The points probed on a NONLINEAR f from a bracket of the given width around 1.
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Nonlinear on purpose: on a linear f the two spaces coincide EXACTLY (deviation
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0.0, measured 2026-09-20), because the derived scale makes the step the Newton
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step and that lands on the root in either space — so a linear probe cannot see
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the deviation at all."""
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calls = []
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g = fun or (lambda t: t * t * t - 1.0)
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def f(x):
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calls.append(x)
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return g(x)
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P.pure_root(f, 1.0 - width, 1.0 + width, xtol=1e-14, maxfev=200,
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similarity="ratio", scale="derived", guard="none", space=space)
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return calls
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def test_G1_the_transform_carries_no_chosen_constant():
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src = "".join(inspect.getsource(fn) for fn in (P._log_map, P._log_unmap, P._log_space_step))
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literals = set(re.findall(r"(?<![\w.])\d+\.\d+(?![\w.])", src))
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assert literals <= {"0.0", "1.0"}, f"chosen constants in the transform: {literals}"
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# and the unit really is the caller's tolerance, not something invented inside
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call_site = inspect.getsource(P.pure_root)
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assert "_log_space_step(S, x, fx, far, slope, c_near, xtol)" in call_site
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def test_G1_the_near_end_is_read_from_the_data_not_fixed():
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call_site = inspect.getsource(P.pure_root)
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assert "c_near = A if abs(FA) <= abs(FB) else B" in call_site
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def test_the_transform_round_trips():
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for s in (1e-12, 1e-6, 1.0, 1e6):
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for c in (-3.0, 0.0, 7.5):
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for t in (c - 1e3, c - 1e-9, c, c + 1e-9, c + 1e3):
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u = P._log_map(t, c, s)
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back = P._log_unmap(u, c, s)
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assert math.isclose(back, t, rel_tol=1e-12, abs_tol=1e-12)
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def test_G2_deviation_from_the_x_space_step_is_second_order_in_the_bracket():
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"""The march needs a RATIO of distances and identity needs an ABSOLUTE unit, so the
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strict identity gate is unreachable (FINDINGS §1). What must hold is that the
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deviation SHRINKS as the bracket collapses — otherwise the wide-bracket families
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would be bought at the price of the canonical set."""
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dev = {}
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for width in (1e-2, 1e-3, 1e-4):
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xs_x = _steps(width, "x")
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xs_log = _steps(width, "log")
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# the first probing evaluations are the bracket ends; compare the first step
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i = 2
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assert len(xs_x) > i and len(xs_log) > i
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dev[width] = abs(xs_log[i] - xs_x[i]) / width
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# exact zero is a STRONGER pass than a shrinking deviation, so it is allowed
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assert dev[1e-3] <= dev[1e-2] / 3.0 or dev[1e-2] == 0.0, dev
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assert dev[1e-4] <= dev[1e-3] / 3.0 or dev[1e-3] == 0.0, dev
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def test_the_mode_is_rejected_where_it_cannot_be_read():
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with pytest.raises(ValueError):
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P.pure_root(lambda x: x, -1.0, 1.0, 1e-10, 100, scale="bracket", space="log")
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with pytest.raises(ValueError):
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P.pure_root(lambda x: x, -1.0, 1.0, 1e-10, 100, space="nope")
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def test_the_mode_still_solves_both_a_narrow_and_a_wide_bracket():
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for lo, hi in ((0.5, 1.5), (-1e12, 3.0)):
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x, nfev, ok = P.pure_root(lambda t: t - 1.0, lo, hi, xtol=1e-10, maxfev=500,
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similarity="ratio", scale="derived3", guard="credit",
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space="log")
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assert ok and abs(x - 1.0) < 1e-8, (lo, hi, x, nfev, ok)
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def test_x_space_is_untouched_by_the_new_parameter():
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"""The published configuration must be bit-identical with the default space."""
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for lo, hi in ((0.5, 1.5), (0.5, 1e6)): # both brackets must straddle sqrt(2)
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a = P.pure_root(lambda t: t * t - 2.0, lo, hi, 1e-12, 300,
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similarity="ratio", scale="derived3", guard="credit")
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b = P.pure_root(lambda t: t * t - 2.0, lo, hi, 1e-12, 300,
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similarity="ratio", scale="derived3", guard="credit", space="x")
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assert a == b
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