Elamur Groupantsmath-calc-checks
The groupant beside math/src/calc.rs in the Mova repository: what the code computes, what it never does, how to go back from its outputs, its invariants, cost and checks.
Facts
Implementation material. A Mova code model describes this code at one source revision: partial models, finite checks and their stated scope. It is not a reviewed general exposition, and its labels are shown as written, never raised.
Components
| component | label | where |
|---|---|---|
| approximant | partial | approximant |
| ast | partial | ../syntax.json |
| composition | partial | model.md |
| cost | partial | Cost |
| descriptant | present | descriptant |
| invariant | partial | invariant |
| tests | executed bounded checks | tests |
Obernants
The typed relations around the forward model: the behaviour complement (what the code never does), the reverse reconstruction (every input compatible with an output) and specialised views.
| id | type | label | where |
|---|---|---|---|
behavior_complement | behavior_complement | partial source derived model | behavior_complement |
reverse_reconstruction | reverse_reconstruction | partial source derived model | reverse_reconstruction |
priority_relation | priority_relation | partial source derived model | priority_relation |
finite_tolerance | finite_tolerance | partial source derived model | finite_tolerance |
factorial_operand_domain | factorial_operand_domain | partial source derived model | factorial_operand_domain |
availability_boundary | availability_boundary | partial source derived model | availability_boundary |
Parts
Model text
descriptant
math-calc-checks
approx computes supported f64 expressions; fingerprint computes integer residues; independent prefers exact integer residues then finite f64. Matching is many-to-one, tolerance1e-9 max(1,|result|). Unavailable or matching checks are not global numerical guarantees.
Epoch 2026-10-31: complete source read, parent AST reused; partial finite evidence only.
approximant
Scoped forward and cost
approx computes supported f64 expressions; fingerprint computes integer residues; independent prefers exact integer residues then finite f64. Matching is many-to-one, tolerance1e-9 max(1,|result|). Unavailable or matching checks are not global numerical guarantees.
No executable percent surrogate claimed.
invariant
Scoped invariant
approx computes supported f64 expressions; fingerprint computes integer residues; independent prefers exact integer residues then finite f64. Matching is many-to-one, tolerance1e-9 max(1,|result|). Unavailable or matching checks are not global numerical guarantees.
Source range[55308,62082) bound by manifest digest. Parent domain applies, not arbitrary public states.
Additional source limits from independent review: range converts span through z_to_u64(...).unwrap_or(0); a positive span>u64 charges0 then loops without per-iteration ticks. Fingerprint factorial reduces its operand first: original operand P61+1 yields residue argument1 and result1, whereas mathematical factorial residue is0. Restrict original factorial operand domain; residue<=2M alone is insufficient. No huge input was executed.
models
Source-scoped typed relations
behavior_complement
For integer result x, a supported fingerprint excludes acceptance when x mod P61 differs from computed fp. Matching excludes no error by a multiple of P61. Unsupported paths return None, not Check{ok:false}.
reverse_reconstruction
Given fingerprint r, compatible claimed integers are {r+k*P61 | k integer}. A finite f64 check admits results within its scaled tolerance. Neither relation identifies the original E or exact result.
priority_relation
independent checks integer fingerprint first and returns it immediately. Only unavailable fingerprint reaches finite f64 comparison; a failing supported fingerprint is not rescued by a floating match.
finite_tolerance
For Q fallback require both a and fx finite and |fx|<1e300, then |a-fx|<=1e-9 max(|fx|,1). R branch compares without this explicit finite prefilter; unsupported approx remains None.
factorial_operand_domain
fingerprint(Fact(a)) fingerprints a first, then computes factorial of residue if <=2M. Correctness needs the original operand admitted in the small natural domain; original P61+1 maps to1! residue1 although true factorial residue0. This huge case is source-derived, not executed.
availability_boundary
approx supports arithmetic/selected calls but not lists/booleans/index/ranged functions; mod/floor/ceil reject magnitudes>=4.5e15. fingerprint supports integer addition, subtraction, multiplication, natural powers, factorial and negation; division returns None, so independent may instead use its floating fallback. Power evaluates the exponent via a fresh Env.
tests
Evidence
See ../tests.md for actual checks and source mutant; this fragment adds no runtime test.
approx computes supported f64 expressions; fingerprint computes integer residues; independent prefers exact integer residues then finite f64. Matching is many-to-one, tolerance1e-9 max(1,|result|). Unavailable or matching checks are not global numerical guarantees.
wave34-composition
Check descendant composition
The residue-fibers child feeds independent only for an integer exact result. A supported residue comparison returns immediately even on disagreement; f64 fallback runs only when fingerprint is unavailable. The integer result is reduced by the same modulus, so accepted claims inhabit a residue class and may differ by P61. Unsupported result types yield no check. The child also evaluates power exponents in a fresh Env and the factorial argument reduction remains a documented domain gap.
Parent compatible antecedents must preserve the supported/unsupported branch, not only the numeric residue. A failed fingerprint cannot be repaired by a favorable floating recomputation in the parent. Historical approximate and finite-tolerance models remain distinct; no total numerical certificate is inferred.
Cost
Use the reached fingerprint cost, then one result reduction and comparison. Only an unavailable fingerprint adds approximate-expression traversal. Avoid adding both branches when fingerprint succeeds. Big-integer reduction and cloned exponent variables contribute outside the modular multiplication count.
This page in Markdown → https://md.groupants.elamur.ai/free/en/mova/math/src/calc.rs.groupant/checks.groupant/