---
title: "mlab-display — Mova code model"
description: "Mova code model of mlab/src/display.rs: components with their labels, obernants and the model text."
url: "https://groupants.elamur.ai/free/en/mova/mlab/src/display.rs.groupant/"
---
Elamur: [Mova](https://md.mova.elamur.ai/free/en/) · [Dictionary](https://md.dictionary.elamur.ai/free/en/) · [Research](https://md.research.elamur.ai/free/en/) · **Groupants**

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# mlab-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

- **kind:** groupant
- **status:** partial source bound model
- **source:** [`mlab/src/display.rs`](https://github.com/ElamurAI/mova-free/blob/main/mlab/src/display.rs)
- **source SHA-256:** `7c29a46772ca4d47…`
- **repository folder:** [`mlab/src/display.rs.groupant`](https://github.com/ElamurAI/mova-free/tree/main/mlab/src/display.rs.groupant)
- **repository commit:** `48f2e6f74146`

> **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](#approximant) |
| **ast** | partial | `syntax.json` |
| **composition** | partial | [composition](#composition) |
| **cost** | symbolic source derived | [invariant](#invariant) |
| **descriptant** | present | [descriptant](#descriptant) |
| **invariant** | partial | [invariant](#invariant) |
| **tests** | executed bounded checks | [tests](#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](#behavior-complement) |
| `reverse_reconstruction` | reverse_reconstruction | partial source derived model | [reverse_reconstruction](#reverse-reconstruction) |
| `state_invariant` | state_invariant | partial source derived model | [state_invariant](#state-invariant) |
| `failure_precedence` | failure_precedence | partial source derived model | [failure_precedence](#failure-precedence) |
| `representation_transport` | representation_transport | partial source derived model | [representation_transport](#representation-transport) |
| `resource_cost` | resource_cost | partial source derived model | [resource_cost](#resource-cost) |

## Parts

- [mlab-display-format-choice](https://md.groupants.elamur.ai/free/en/mova/mlab/src/display.rs.groupant/format-choice.groupant/)
- [mlab-display-matrix-layout](https://md.groupants.elamur.ai/free/en/mova/mlab/src/display.rs.groupant/matrix-layout.groupant/)

## 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.