Elamur Groupantsmlab-display
The groupant beside mlab/src/display.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 | composition |
| cost | symbolic source derived | invariant |
| 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 |
state_invariant | state_invariant | partial source derived model | state_invariant |
failure_precedence | failure_precedence | partial source derived model | failure_precedence |
representation_transport | representation_transport | partial source derived model | representation_transport |
resource_cost | resource_cost | partial source derived model | resource_cost |
Parts
Model text
descriptant
mlab-display
Octave-style textual display of values, real/complex common formats and function expression unparse.
Modeling epoch — 2026-10-31
Prospective source read preceded edits. Bounded synthetic checks and selected existing safe tests exercise actual code; paired debug/release results and compiled negative-control assertions are retained externally. Frozen scenario, corpus, external measurement, full-school and training effects are unexecuted. Partial lexical syntax supplies no macro-expanded or semantic proof.
approximant
Forward relation
Choose real common format from finite extrema/integrality and precision 5 or 16; render column-major cells as rows, split blocks by floor(80/cell_width). Named output adds labels/blank lines; disp omits numeric empty values and prints char rows.
Domain
Valid Rust value/storage invariants and available bounded resources; exact branch and effect observations only.
Executable approximant gap
No useful percentage-error surrogate is established for these categorical, textual or effectful observations. Supported future caps are 1%, 2%, 5%, 10%; no executable approximation or production substitution is claimed.
invariant
Invariants and costs
Cells use index col*rows+row. All matrix cells share format widths computed across data. Nonfinite names are NaN/Inf/-Inf.
Failure ordering
Public Mat dimensions/storage and scalar index must be valid; inconsistent lengths can panic. Width and formatting allocation are unchecked; no I/O performed here.
Cost
O(elements + emitted characters), O(elements + text) cell buffering; recursive unparse may repeatedly concatenate subtree strings. No measured speed or general relative numeric-error guarantee for text.
composition
Composition
Choose real common format from finite extrema/integrality and precision 5 or 16; render column-major cells as rows, split blocks by floor(80/cell_width). Named output adds labels/blank lines; disp omits numeric empty values and prints char rows.
Logical values use nonzero predicate; char values map codepoints. Precision controls significant digits, but exact integer branch remains integer up to 15 digits.
format-choice
Accumulate finite maxabs/minabs and all_int; all-int branch chooses integer unless digits>15, otherwise fixed versus exponent depends on rounded digit extrema.
Boundary: Nonfinite strings require width at least four in integer/fixed branches; exponent width expands for large exponents.
matrix-layout
Map storage j*r+i into row vectors with common field width, then partition columns into blocks of max(1,80/width).
Boundary: Every row visits columns in increasing order. Last two-column block uses and rather than through header.
Interaction limit
Local fragment relations compose only with valid Value storage, caller error propagation and delegated providers. They do not establish whole-interpreter or host-filesystem guarantees.
models
Typed models — mlab-display
Source-derived partial relations; finite checks do not prove universality.
behavior_complement
Numeric zero formatting excludes a printed negative sign; scalar complex imaginary -0 permits minus while matrix complex comparison excludes it. Empty numeric disp excludes a newline, empty char disp includes one.
reverse_reconstruction
Printed rounded values admit all floating inputs sharing chosen format and rounding bins; labels do not recover types uniquely. unparse loses closure captures and is not a precedence-repairing inverse parser.
state_invariant
Cells use index col*rows+row. All matrix cells share format widths computed across data. Nonfinite names are NaN/Inf/-Inf.
failure_precedence
Public Mat dimensions/storage and scalar index must be valid; inconsistent lengths can panic. Width and formatting allocation are unchecked; no I/O performed here.
representation_transport
Logical values use nonzero predicate; char values map codepoints. Precision controls significant digits, but exact integer branch remains integer up to 15 digits.
resource_cost
O(elements + emitted characters), O(elements + text) cell buffering; recursive unparse may repeatedly concatenate subtree strings. No measured speed or general relative numeric-error guarantee for text.
tests
Evidence and limitations
Selected named outcomes: display::tests::scalars_short, display::tests::matrix_rows. Each ran twice debug and twice release with sorted identical nonempty outcomes and numeric exit 0. Source-specific compiled control exercised "display::tests::scalars_short": compile exit 0, assertion-red exit 101, exact-restored rerun exit 0. External receipts: octopus-wave30-io-2026-10-31 (native-commands.json, positive-receipts.json, controls.json).
Scope: Cells use index col*rows+row. All matrix cells share format widths computed across data. Nonfinite names are NaN/Inf/-Inf.
AST projection generated twice to fresh files and compared byte-for-byte. Runtime evidence is finite and does not establish every branch, allocation failure, backend implementation or effect path. No optimization or speed claim.
This page in Markdown → https://md.groupants.elamur.ai/free/en/mova/mlab/src/display.rs.groupant/