Build, review, migrate, and safely plan MATLAB or GNU Octave numerical workflows, including arrays, tabular/time data, tests, projects, graphics, MAT files, and explicit Python interoperability.

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](references/octave compatibility.md) and [execution/product boundaries](references/executing scripts.md). 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 1. 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. 2. Inventory statically. Scan .m files, opaque artifacts, project paths, required products, and MAT headers before any runtime loads them. 3. Choose code form. Prefer functions with an arguments block for automation. Use scripts only for controlled orchestration and live scripts for reviewed interactive narratives. 4. Make semantics explicit. Record shapes, classes, units, missing value rules, indexing, implicit expansion, RNG algorithm/seed, tolerances, and output formats. 5. Test without hidden state. Keep fixtures synthetic, paths project local, graphics deterministic, and tests independent of base workspace residue. 6. Plan execution. Generate an argv plan, review startup/path effects and licenses, and launch only after explicit approval outside these helpers. 7. 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. Read [programming](references/programming.md). 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](references/matrices arrays.md) and [mathematics](references/mathematics.md). 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](references/data import export.md). 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](references/graphics visualization.md). 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](references/data import export.md). 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](references/programming.md) and [execution/testing](references/executing scripts.md). 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](references/python integration.md). 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 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](references/programming.md) [Matrices, indexing, types, missingness, performance](references/matrices arrays.md) [Numerical methods, tolerances, RNG, toolbox boundaries](references/mathematics.md) [Graphics and exportgraphics ](references/graphics visualization.md) [Import/export, tables/timetables, MAT semantics and safety](references/data import export.md) [MATLAB/Octave command line execution and migration](references/executing scripts.md) [MATLAB and Python interoperability](references/python integration.md) [GNU Octave 11.3.0 compatibility differences](references/octave compatibility.md) Bundled JSON assets are the [project manifest](assets/project manifest template.json), [reproducibility manifest](assets/reproducibility mani