Matlab

MATLAB and GNU Octave

Use this skill to design or review numerical code, migrate MATLAB releases,

prepare reproducible projects, and plan trusted execution. MATLAB and GNU

Octave are distinct products: compatibility is partial, not a license or

behavior guarantee.

Product and license gate

• MATLAB R2026a is proprietary. Do not assume MATLAB, MATLAB Online, a

named toolbox, MATLAB Test, MATLAB Compiler, MATLAB Coder, Parallel Computing

Toolbox, or an add-on is installed, licensed, or available to the user.

• MATLAB Runtime is not MATLAB. It runs compatible applications produced

with MATLAB Compiler; it cannot run arbitrary source or host MATLAB Engine

for Python. Building artifacts needs the applicable licensed compiler and

every product used by the source.

• GNU Octave 11.3.0 is free software under GPLv3+. Octave packages are not

MATLAB toolboxes. Similar names do not imply API, numerical, graphics, or

licensing equivalence.

• Ask which runtime, release, platform, installed products, and license context

the user actually has. Treat availability as unknown until confirmed.

See Octave compatibility and

execution/product boundaries.

Nonnegotiable safety boundary

Never run an untrusted .m, .mlx, MEX binary, MAT file, project startup or

shutdown action, package installer, or generated artifact. Static review does

not prove safety.

Treat these as execution or code-loading surfaces:

• eval, evalin, assignin, text-derived feval, str2func, callbacks,

timers, app callbacks, and dynamically modified paths;

• system, unix, dos, shell escape !, Java, .NET, Python (py.*,

pyrun, pyrunfile), MEX, and native libraries;

• mex, codegen, MATLAB Compiler, build tasks, package/project startup, and

generated code;

• load, object deserialization (loadobj, custom serialization), function

handles, Java/System objects, and class code reachable from MAT files.

.mlx is an opaque archive for this toolkit and MEX is native executable code.

Do not use Python pickle for exchange. Inspect first, isolate when appropriate,

obtain explicit approval, then invoke a user-confirmed executable and license.

Bundled scripts are static or dry-run tools: none launches MATLAB, Octave,

Python Engine, a compiler, or a subprocess.

Default workflow

• Clarify target. Record MATLAB release or Octave version, OS/architecture,

base product versus required toolboxes/packages, expected inputs/outputs,

numerical tolerances, and whether execution is authorized.

• Inventory statically. Scan .m files, opaque artifacts, project paths,

required products, and MAT headers before any runtime loads them.

• Choose code form. Prefer functions with an arguments block for

automation. Use scripts only for controlled orchestration and live scripts

for reviewed interactive narratives.

• Make semantics explicit. Record shapes, classes, units, missing-value

rules, indexing, implicit expansion, RNG algorithm/seed, tolerances, and

output formats.

• Test without hidden state. Keep fixtures synthetic, paths project-local,

graphics deterministic, and tests independent of base-workspace residue.

• Plan execution. Generate an argv plan, review startup/path effects and

licenses, and launch only after explicit approval outside these helpers.

• Capture provenance. Hash named inputs/code and record release, products,

RNG policy, tolerances, and command plan without dumping the environment.

Language and data checklist

Scripts, functions, and live scripts

• Scripts share the caller/base workspace and leave variables behind.

Functions have local workspaces and explicit inputs/outputs.

• Live scripts (.mlx) mix code and rich output but are not plain-text

review artifacts. Export reviewed code to .m for static inspection.

• Avoid clear all, broad addpath(genpath(...)), dependence on pwd, global

variables, and silent name shadowing. Use project roots and fullfile.

• Validate sizes, classes, and values in arguments blocks. Remember that

type declarations can convert inputs; validators check without converting.

• A main function file should match the main function name. Local functions

are private to the file; since R2024a they can appear anywhere in a script

outside conditional contexts.

function y = scaleSignal(x, options)
arguments
    x (:,1) double {mustBeFinite}
    options.Scale (1,1) double {mustBeFinite, mustBeNonzero} = 1
end
y = x .* options.Scale;
end

Read programming.

Arrays, indexing, and numerics

• MATLAB uses 1-based, column-major indexing. A(i,j), A(k), A(:,j),

A{...}, and A.(name) have different semantics.

• *, /, \, and ^ are matrix operations; dotted forms are

element-wise. Use A\b, not inv(A)*b.

• Since R2016b, compatible dimensions expand implicitly. Assert intended shape

before operations that could accidentally form an outer result.

• Preallocate when output size is known, but do not vectorize at the cost of

huge temporaries or unreadable code. Measure with timeit or the profiler.

• Compare floating-point results with domain-chosen absolute and relative

tolerances, not blanket == or a magic multiple of eps.

• Pin both random algorithm and seed. Use named RandStream substreams for

independent parallel work; do not use time-based rng("shuffle") for a

reproducibility claim.

Read arrays and

mathematics.

Tables, timetables, and missing values

• A table has named, equal-height variables that may have different types.

T(rows,vars) returns a table; T{rows,vars} extracts contents; T.Var

selects one variable.

• A timetable additionally has row times. Sort, validate time zones and

uniqueness, then use retime/synchronize intentionally.

• Missing sentinels are type-specific: NaN, NaT, <missing>,

<undefined>, and empty character vectors. Integer and logical arrays have

no standard missing sentinel.

• Define import options rather than relying on inference for production data.

Preserve units, time zones, variable names, encodings, and missing rules.

Read data import/export.

Graphics and export

Use explicit figure/axes handles and tiledlayout; label units; set limits,

color scales, font sizes, and colormaps deliberately. Prefer exportgraphics

over saveas for publication output. In R2026a it exports raster, PDF/EPS/EMF,

SVG, GIF, and interactive HTML; format capabilities differ. Specify

ContentType="vector" for suitable PDF/SVG-style output and Resolution for

raster output. Review accessibility and embedded-raster behavior.

Read graphics and export.

MAT files and exchange

• Version 7 is the normal save default; matfile creates 7.3 by default.

Versions 4/6/7/7.3 differ in types, compression, and per-variable limits.

• Version 7.3 is HDF5-based, not an arbitrary HDF5 interchange contract.

Partial access and chunking can help large arrays.

• Never load an untrusted MAT file. Inventory headers/datasets first. Objects

can invoke class deserialization behavior; opaque/function/native content

requires escalation.

• Prefer CSV/JSON/Parquet/HDF5 with a documented schema for simple exchange.

Do not rename pickle payloads as MAT files and do not deserialize pickle.

Read data import/export.

Projects, analysis, and tests

• Use MATLAB Projects for controlled paths, startup/shutdown tasks,

dependencies, source control, and reproducible entry points. Review project

actions before opening an untrusted project.

• matlab.codetools.requiredFilesAndProducts and Dependency Analyzer are

static approximations; dynamic dispatch can cause misses or false positives.

A required-product report does not prove a license is available.

• Use Code Analyzer (codeIssues; legacy text workflows can use checkcode)

and codeCompatibilityReport before migration.

• Base MATLAB includes script-, function-, and class-based

matlab.unittest workflows. Parallel runs require Parallel Computing

Toolbox. Dependency-based selection, richer quality dashboards, generated

tests, and advanced coverage/equivalence features can require MATLAB Test or

other products.

• R2026a runtests automatically opens and later closes a project when target

tests belong to a project that is not already open. Account for startup and

shutdown actions before using this behavior.

Read programming and

execution/testing.

Python integration, pinned to R2026a

• R2026a supports 64-bit CPython 3.9-3.13 for MATLAB Interface to Python,

MATLAB Engine for Python, and MATLAB Compiler SDK for Python.

• The current R2026a PyPI package reviewed here is

matlabengine==26.1.12 (released 2026-05-08). It requires an installed

R2026a; MATLAB Runtime alone is insufficient. R2026a also ships a

preinstalled Engine distribution under one named matlabroot path.

• Package installation does not grant MATLAB or toolbox licenses. Configure

one named interpreter/executable; do not print the full environment,

PATH, PYTHONPATH, or credentials.

• pyenv controls MATLAB-to-Python interpreter selection. In-process Python

generally requires restarting MATLAB to switch; out-of-process Python can

be terminated and reconfigured.

• Starting Engine is an explicit execution action:

matlab.engine.start_matlab() starts a MATLAB process and can check out a

license. Never call it merely to probe availability.

• Verify conversion semantics for NumPy arrays, pandas DataFrames,

tables/timetables, strings/missing values, datetime/duration, dictionaries,

shape/order, and unsupported sparse/object/categorical cases.

Read Python integration.

Local helper CLIs

Every helper is network-free, bounded, symlink-rejecting, and nonexecuting.

Run from this skill directory with Python 3.11+. Bash is allowed only to invoke

these Python CLIs and validation commands; never use it to execute a generated

MATLAB/Octave argv plan or untrusted artifact.

| Helper | Purpose |

|---|---|

| scripts/plan_batch_command.py | Produce reviewed MATLAB/Octave argv; never execute |

| scripts/scan_m_code.py | Scan .m text and flag opaque .mlx/MEX risks |

| scripts/validate_project_manifest.py | Validate paths and declared product/license status |

| scripts/inventory_mat_file.py | Header/metadata inventory; never call loadmat |

| scripts/plan_python_compatibility.py | Check R2026a CPython/Engine compatibility |

| scripts/reproducibility_report.py | Hash named local artifacts and emit a bounded report |

| scripts/generate_function_scaffold.py | Dry-run or create function and unit-test scaffolds |

python scripts/scan_m_code.py path/to/source --root path/to/project
python scripts/plan_batch_command.py matlab script path/to/main.m --root path/to/project
python scripts/validate_project_manifest.py project-manifest.json --root path/to/project
python scripts/inventory_mat_file.py data.mat --root path/to/project
python scripts/plan_python_compatibility.py --python-version 3.13
python scripts/reproducibility_report.py --root path/to/project --file src/analyze.m
python scripts/generate_function_scaffold.py analyzeSignal --root path/to/project

The scaffold generator defaults to dry-run; writing requires --write and

refuses collisions. SciPy and h5py are optional inventory backends; if

authorized, add exact reviewed versions to the caller's project lockfile.

They are not required for --help or header-only inventory, and this skill

does not perform package installation.

References

• Programming, workspaces, projects, analysis, tests
• Matrices, indexing, types, missingness, performance
• Numerical methods, tolerances, RNG, toolbox boundaries
• Graphics and exportgraphics
• Import/export, tables/timetables, MAT semantics and safety
• MATLAB/Octave command-line execution and migration
• MATLAB and Python interoperability
• GNU Octave 11.3.0 compatibility differences

Bundled JSON assets are the project manifest,

reproducibility manifest, and

R2026a Python table. There is no

templates/ directory and no Markdown file is loaded from assets/;

local-link tests enforce this package contract.

Primary sources (verified 2026-07-23)

• MATLAB R2026a documentation
• MATLAB R2026a release notes
• R2026a system requirements
• Python compatibility by release
• MATLAB Engine installation
• GNU Octave 11.3.0 release
• GNU Octave current manual