Matlab Modernize Code
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AutoGineer summary
Written by AutoGineer from the skill’s own files, not by the author
This skill provides a systematic approach to modernizing MATLAB codebases. It acts as a resolver for issues identified by the check_matlab_code MCP tool, which flags functions that are removed, discouraged, or slated for future removal. By replacing outdated APIs and anti-patterns with current, performant, and secure alternatives, this skill helps maintain code longevity and compatibility with modern MATLAB releases.
What it does
- Identifies and replaces removed or discouraged MATLAB functions.
- Refactors anti-patterns like eval, clear all, and str2num.
- Provides migration paths for file I/O, UI components, and signal processing.
- Integrates with static analysis results from check_matlab_code.
- Offers domain-specific guidance for deep learning, audio/video, and communications.
- Promotes modern design patterns like table-based workflows and arguments blocks.
When to use it
- When check_matlab_code reports lifecycle diagnostics (info, warning, or error).
- When migrating legacy scripts to newer MATLAB versions.
- When replacing discouraged patterns like containers.Map or bsxfun.
- When updating code to use modern APIs like readmatrix or datetime.
- When starting new projects to ensure best-practice implementation from the start.
Advantages
- Ensures code compatibility with current and future MATLAB releases.
- Improves code performance and readability by using optimized modern APIs.
- Enhances security by eliminating dangerous patterns like unrestricted eval.
- Reduces technical debt by systematically removing deprecated dependencies.
- Provides clear, tested migration paths for common domain-specific tasks.
Usage examples
- “Modernize this legacy file I/O code: [M, t] = xlsread('data.xlsx');”
- The agent replaces the call with the modern readtable function: T = readtable('data.xlsx');
- “How do I replace this discouraged eval pattern: eval(['A' int2str(n) '=magic(n);']);”
- The agent suggests using a cell array for dynamic indexing: A = cell(10,1); for n = 1:10, A{n} = magic(n); end
- “Update my audio code that uses the removed wavread function.”
- The agent provides the modern replacement using audioread, including handling for sample ranges and native formats.
- “Replace my old BPSK modulator object with the modern function call.”
- The agent replaces the comm.BPSKModulator object instantiation with the direct pskmod(data, 2) function call.
Install
Download the skill as a ZIP:
https://mp-staging.autogineer.com/agent-skills/matlab/matlab-modernize-code/downloadUnzip it into the cross-client skills folder of your project:
mkdir -p .agents/skills && unzip matlab-modernize-code.zip -d .agents/skills
Documentation by MathWorks
Code Modernization
Replace removed or discouraged MATLAB functions and anti-patterns with modern equivalents. This skill is the resolver — the MCP tool check_matlab_code (MATLAB's Code Analyzer) is the detector.
Terms used in this skill:
Removed — the function is no longer in MATLAB; calling it errors.
Discouraged — the function still works, but a better API exists. It may or may not be slated for removal in a future release.
When to Use
check_matlab_codereports a lifecycle diagnostic — any of these three wordings, matched case-insensitively (STRMATCH is not recommendedis the same signal as the lowercase form):'X' is not recommended...(severity: info)'X' will be removed in a future release...(severity: warning)'X' has been removed...(severity: error — the code errors today)
Code uses a discouraged pattern Code Analyzer does not flag — e.g.
containers.Map,bsxfun,str2num,eval,clear all— scan the source, not just the diagnostics (see Conventions)User asks to modernize, migrate, or update old MATLAB code
Code uses functions listed in the quick reference table below
After static analysis reveals removed or discouraged API usage
Writing new code in a domain that has known removed or discouraged patterns
When NOT to Use
This skill swaps removed or discouraged APIs for modern equivalents. It does not:
Review code quality broadly
Debug runtime behavior (removed-function errors excepted — those are modernization fixes)
Optimize already-correct code for speed → hand off to
matlab-optimize-performanceWrite or migrate function input/output validation (
argumentsblocks,inputParser/validateattributes→mustBe*validators, repeating args, name-value forwarding) → hand off tomatlab-validate-function-arguments
Quick Reference: Removed, Discouraged & Anti-Patterns
| Topic | Recommendation | Since | Category | Rationale |
|---|---|---|---|---|
csvread / dlmread | readmatrix | R2019a | File I/O | |
csvwrite / dlmwrite | writematrix | R2019a | File I/O | |
xlsread | readtable, readmatrix | R2019a | File I/O | |
xlswrite | writetable, writematrix | R2019a | File I/O | |
datenum / datestr / now | datetime (use string/char to format) | R2022b | Date/Time (Not recommended) | Flagged by Code Analyzer |
eval / evalc / evalin | Dynamic field names s.(name), function handles / feval, cells for sequential names | — | Anti-pattern | Not compiled (slow); can overwrite workspace vars; hard to debug; injection risk |
str2num | str2num(text, Evaluation="restricted") | R2022a | Security | Unrestricted form runs input via eval (injection risk); see references |
uicontrol | uibutton, uidropdown, etc. | R2016a | UI/App | |
guide | appdesigner | R2025a | UI (Removed) | |
strmatch | startsWith, matches | R2019b | Strings | |
clear all | clearvars | — | Workspace | Clears functions from memory; forces recompilation |
datestrnuance:datestr's job was to format a date as text, so its modern replacement isstring(dt)/char(dt)or settingdt.Format— not a baredatetime(...)call. Usedatetimeto replacedatenum/now(the numeric/serial-date path). Neither is removed; both are Code Analyzer "not recommended" as of R2022b.s = datestr(t, 'yyyy-mm-dd HH:MM:SS'); % old s = string(t, 'yyyy-MM-dd HH:mm:ss'); % new — note the specifiers change: % datetime uses MM=month, mm=minute (datestr had mm=month, MM=minute)
Modern Design Patterns
Prefer these in all new code:
Table-Based Workflows
data = readtable('sensors.csv');
data.Timestamp = datetime(data.Timestamp);
data.Status = categorical(data.Status);
recentData = data(data.Timestamp > datetime('today') - days(7), :);
summary = groupsummary(recentData, 'SensorID', 'mean', 'Value');String Arrays (not char arrays)
name = "John"; % not 'John'
names = ["John", "Jane", "Bob"]; % not {'John','Jane','Bob'}
fullName = firstName + " " + lastName; % not [first,' ',last]
idx = contains(names, "Jo"); % not cellfun + strfindArguments Block (not nargin/varargin)
function result = processData(data, options)
arguments
data (:,:) double
options.Method (1,1) string {mustBeMember(options.Method, ["fast","accurate"])} = "fast"
options.Verbose (1,1) logical = false
end
endKey Migrations
File I/O: csvread/xlsread → readmatrix/readtable
% Old → Modern
M = csvread('data.csv'); % M = readmatrix("data.csv");
M = dlmread('data.txt','\t'); % M = readmatrix("data.txt", Delimiter="\t");
[n,t,r] = xlsread('f.xlsx'); % T = readtable("f.xlsx");
csvwrite('out.csv', M); % writematrix(M, "out.csv");
xlswrite('out.xlsx', data); % writetable(T, "out.xlsx");eval → Structured Alternatives
Avoid eval/evalc/evalin: the text isn't compiled (slower), can silently overwrite workspace
variables, and is hard to read/debug. Match the intent to a construct — see
references/core-functions-guidance.md for the full set (sequential names, sprintf filenames,
try/catch).
% Old: eval([varName ' = 42;']); -> dynamic field name
s.(varName) = 42;
% Old: result = eval(['process_' method '(x)']); -> handle dispatch table
handlers.fast = @processFast;
handlers.slow = @processSlow;
result = handlers.(method)(x);
% Old: for n=1:10, eval(['A' int2str(n) '=magic(n);']); end -> index a cell
A = cell(10,1);
for n = 1:10, A{n} = magic(n); endReferences
Load these when working in a specific domain:
| Load when... | Reference |
|---|---|
Core MATLAB functions (file I/O, strings, UI); security anti-patterns (eval/str2num), containers.Map→dictionary, bsxfun→implicit expansion | references/core-functions-guidance.md |
| Deep Learning (trainNetwork→trainnet, LayerGraph/SeriesNetwork/DAGNetwork→dlnetwork, classify, activations) | references/deep-learning-guidance.md |
| Signal processing functions | references/signal-processing-guidance.md |
| Audio/video I/O migration (wavread, aviread) | references/audio-video-guidance.md |
| Optimization toolbox (optimset, optimtool) | references/optimization-guidance.md |
| Control systems plot options | references/control-systems-guidance.md |
| Image processing ROI objects | references/image-processing-guidance.md |
| Statistics/ML (svmtrain, dataset, classregtree) | references/statistics-ml-guidance.md |
| Communications System objects | references/communications-guidance.md |
| Mapping Toolbox (webmap, wmmarker, wmline, geotiffread, mfwdtran, makerefmat) | references/mapping-guidance.md |
Conventions
Always run
check_matlab_codefirst — let static analysis find removed or discouraged usageAfter running it, scan the source for patterns the Code Analyzer may under-flag:
str2num(framed only as a perf tip);containers.Map(see next point).containers.Mapis not flagged bycheck_matlab_code. A plain script using it returns zero diagnostics; acontainers.Mapproperty default surfaces only a handle-default-sharing warning ("all instances share the same object data"). The detect-first workflow will not find this migration — treat anycontainers.Mapusage, and that handle-sharing warning on a property, as acontainers.Map→dictionarytrigger.subplotis not deprecated or discouraged. It is fully supported and is never flagged bycheck_matlab_code.tiledlayout/nexttileis a preferred alternative for new code, not a required migration — do not tell the user to replace workingsubplotcode.Fix removed or discouraged patterns before other code quality issues
When writing new code, use the modern pattern from the start — don't write legacy code and fix it later
A
'X' has been removeddiagnostic (severityerror) means the function errors today — treat it as a break-fix modernization, ahead of "not recommended" (info) and "will be removed" (warning) casesWhen migrating, test the modern replacement against the old behavior to confirm equivalence
Legacy
.mfiles are often Windows-1252 encoded. After an edit, verify non-ASCII characters (°,µ,±) survived — a diff showing an unrelated one-line change on a comment or string is usually a re-encoded byte, not your edit.Consult the domain-specific reference file for detailed migration patterns with code examples
Copyright 2026 The MathWorks, Inc.
Files
- ATTRIBUTION.mdAdded by AutoGineer1.0 KiB
- LICENSELicence file added by AutoGineer1.4 KiB
- SKILL.md9.7 KiB
- manifest.yaml1.1 KiB
- references/audio-video-guidance.md9.4 KiB
- references/communications-guidance.md8.5 KiB
- references/control-systems-guidance.md5.0 KiB
- references/core-functions-guidance.md22.1 KiB
- references/deep-learning-guidance.md3.3 KiB
- references/image-processing-guidance.md6.9 KiB
- references/mapping-guidance.md14.5 KiB
- references/optimization-guidance.md6.0 KiB
- references/signal-processing-guidance.md5.0 KiB
- references/statistics-ml-guidance.md8.0 KiB
references/audio-video-guidance.md
Audio/Video I/O Modernization
Quick Reference: Function Mappings
Since gives the removal release for removed functions (all discouraged years earlier).
| Topic | Recommendation | Since | Status |
|---|---|---|---|
wavread | audioread | R2015b | Removed |
wavwrite | audiowrite | R2015b | Removed |
wavfinfo | audioinfo | R2015b | Removed |
wavplay | audioplayer | R2015b | Removed |
wavrecord | audiorecorder | R2015b | Removed |
aviread | VideoReader | R2015b | Removed |
avifile | VideoWriter | R2015b | Removed |
mmreader | VideoReader | R2014a | Removed |
aviinfo | VideoReader | R2010b | Not Recommended, will be removed |
mmfileinfo | — (current function) | — | Supported — not discouraged |
Audio File Reading
wavread → audioread
Status: wavread removed. Use audioread.
Old Pattern (Will Not Work):
% REMOVED: wavread no longer exists
[y, fs] = wavread('audio.wav');
[y, fs, nbits] = wavread('audio.wav');
y = wavread('audio.wav', [1000 5000]); % Read samples 1000-5000Modern Pattern (Use This):
% Read entire file
[y, fs] = audioread("audio.wav");
% Read specific sample range
[y, fs] = audioread("audio.wav", [1000 5000]);
% Get native format (for bit depth)
[y, fs] = audioread("audio.wav", "native");
info = audioinfo("audio.wav"); % Contains BitsPerSampleWhy Modern is Better:
Supports multiple formats: WAV, FLAC, MP3, MPEG-4 AAC, OGG, OPUS
Cross-platform compatibility (no platform-specific quirks)
Better large file handling
Native format preservation option
Migration Notes:
audioreadreturns audio normalized to [-1, 1] by defaultUse
'native'option to get original integer formatUse
audioinfoseparately to get bit depth and other metadata
wavfinfo → audioinfo
Status: wavfinfo removed. Use audioinfo.
Old Pattern (Will Not Work):
% REMOVED: wavfinfo no longer exists
[size, fs, nbits, opts] = wavfinfo('audio.wav');Modern Pattern (Use This):
% Get complete audio file information
info = audioinfo("audio.wav");
% Access specific properties
fs = info.SampleRate;
numSamples = info.TotalSamples;
duration = info.Duration;
numChannels = info.NumChannels;
bitsPerSample = info.BitsPerSample;Why Modern is Better:
Returns structured information (easier to work with)
Supports all audio formats MATLAB can read
More comprehensive metadata
Audio File Writing
wavwrite → audiowrite
Status: wavwrite removed. Use audiowrite.
Old Pattern (Will Not Work):
% REMOVED: wavwrite no longer exists
wavwrite(y, fs, 'output.wav');
wavwrite(y, fs, 16, 'output.wav'); % 16-bitModern Pattern (Use This):
% Write audio file (default format)
audiowrite("output.wav", y, fs);
% Specify bit depth
audiowrite("output.wav", y, fs, BitsPerSample=16);
% Write to different formats
audiowrite("output.flac", y, fs); % FLAC (lossless)
audiowrite("output.ogg", y, fs); % Ogg Vorbis
audiowrite("output.m4a", y, fs); % MPEG-4 AACWhy Modern is Better:
Multiple output format support
Quality settings for compressed formats
Better metadata support
Audio Playback
wavplay → audioplayer
Status: wavplay removed. Use audioplayer object.
Old Pattern (Will Not Work):
% REMOVED: wavplay no longer exists
wavplay(y, fs);
wavplay(y, fs, 'sync'); % Synchronous playbackModern Pattern (Use This):
% Create audio player object
player = audioplayer(y, fs);
% Play asynchronously (non-blocking)
play(player);
% Play synchronously (blocking) - use playblocking
playblocking(player);
% Control playback
pause(player);
resume(player);
stop(player);
% Play specific range (sample indices)
play(player, [1000 5000]);
% Clean up
clear player;Why Modern is Better:
Non-blocking by default (better for GUIs)
Playback control (pause, resume, stop)
Supports callbacks during playback
Can query playback position
Callback Example:
player = audioplayer(y, fs);
player.StopFcn = @(~,~) disp("Playback complete");
play(player);Audio Recording
wavrecord → audiorecorder
Status: wavrecord removed. Use audiorecorder object.
Old Pattern (Will Not Work):
% REMOVED: wavrecord no longer exists
y = wavrecord(n, fs); % Record n samples
y = wavrecord(n, fs, ch); % Specify channels
y = wavrecord(n, fs, ch, nbits);Modern Pattern (Use This):
% Create recorder object
recorder = audiorecorder(fs, nBits, nChannels);
% Record for specific duration
recordblocking(recorder, duration); % Blocking record
% Or record asynchronously
record(recorder);
pause(duration); % Or wait for user input
stop(recorder);
% Get recorded data
y = getaudiodata(recorder);
% Get data in specific format
y = getaudiodata(recorder, "double");
y = getaudiodata(recorder, "int16");
% Clean up
clear recorder;Why Modern is Better:
Non-blocking recording option
Can pause and resume recording
Real-time audio data access
Callback support for monitoring
Real-Time Monitoring Example:
recorder = audiorecorder(44100, 16, 1);
recorder.TimerFcn = @(~,~) plotAudio(recorder);
recorder.TimerPeriod = 0.1;
record(recorder);Video File Reading
aviread, aviinfo → VideoReader
Status: aviread was removed in R2015b. aviinfo is not recommended and will be removed in
a future release — it still runs today, but migrate it to VideoReader now.
Old Pattern (avoid — aviread errors, aviinfo is discouraged):
% REMOVED (R2015b): aviread no longer exists
mov = aviread('video.avi');
frame = aviread('video.avi', 10); % Read frame 10
% NOT RECOMMENDED: aviinfo still runs but will be removed
info = aviinfo('video.avi');Modern Pattern (Use This):
% Create VideoReader object
v = VideoReader("video.mp4");
% Get video properties
numFrames = v.NumFrames;
frameRate = v.FrameRate;
duration = v.Duration;
width = v.Width;
height = v.Height;
% Read all frames
while hasFrame(v)
frame = readFrame(v);
% Process frame
end
% Read specific frame (R2014b+)
frame = read(v, 10); % Frame 10
% Read range of frames
frames = read(v, [10 20]); % Frames 10-20
% Seek to time position
v.CurrentTime = 5.0; % Jump to 5 seconds
frame = readFrame(v);Why Modern is Better:
Supports many formats: MP4, AVI, MOV, MKV, WMV, etc.
Time-based and frame-based access
Hardware-accelerated decoding
Better memory management
Reading Large Videos Efficiently:
v = VideoReader("video.mp4");
% Process frame-by-frame to avoid loading entire video
while hasFrame(v)
frame = readFrame(v);
processedFrame = myProcessing(frame);
endVideo File Writing
avifile → VideoWriter
Status: avifile removed. Use VideoWriter.
Old Pattern (Will Not Work):
% REMOVED: avifile no longer exists
aviobj = avifile('output.avi');
aviobj.FPS = 30;
for i = 1:numFrames
aviobj = addframe(aviobj, frame);
end
aviobj = close(aviobj);Modern Pattern (Use This):
% Create VideoWriter object
v = VideoWriter("output.mp4", "MPEG-4");
v.FrameRate = 30;
v.Quality = 90; % For compressed formats
% Open, write frames, close
open(v);
for i = 1:numFrames
frame = getFrame(i); % Your frame generation
writeVideo(v, frame);
end
close(v);Output Format Options:
% Uncompressed AVI
v = VideoWriter("output.avi", "Uncompressed AVI");
% Motion JPEG AVI
v = VideoWriter("output.avi", "Motion JPEG AVI");
% MPEG-4 (requires license on some platforms)
v = VideoWriter("output.mp4", "MPEG-4");
% Grayscale AVI
v = VideoWriter("output.avi", "Grayscale AVI");
% Indexed AVI (with colormap)
v = VideoWriter("output.avi", "Indexed AVI");Why Modern is Better:
Multiple format support
Quality control for compressed video
Frame rate and resolution control
Better error handling
mmreader → VideoReader
Status: mmreader was removed in R2014a (discouraged since R2010b). Use VideoReader.
mmreader was an early multimedia reader that has been fully replaced by VideoReader.
Note:
mmfileinfois not removed — it is a current, supported function that returns information about a multimedia file. It is not discouraged; there is no need to migrate away from it.
Complete Audio Processing Example
Modern Audio Processing Workflow:
% Read audio
[signal, fs] = audioread("input.wav");
% Get file info
info = audioinfo("input.wav");
fprintf("Duration: %.2f seconds, Channels: %d\n", info.Duration, info.NumChannels);
% Process (example: apply gain)
processed = signal*0.8;
% Write output
audiowrite("output.wav", processed, fs, BitsPerSample=24);
% Play result
player = audioplayer(processed, fs);
playblocking(player);Complete Video Processing Example
Modern Video Processing Workflow:
% Read video
reader = VideoReader("input.mp4");
% Create output
writer = VideoWriter("output.mp4", "MPEG-4");
writer.FrameRate = reader.FrameRate;
open(writer);
% Process frame-by-frame
while hasFrame(reader)
frame = readFrame(reader);
% Example: Convert to grayscale
grayFrame = rgb2gray(frame);
grayFrame = repmat(grayFrame, 1, 1, 3); % Back to RGB for writing
writeVideo(writer, grayFrame);
end
close(writer);Copyright 2026 The MathWorks, Inc.
Requirements and compatibility
Works with: Claude Code, Claude apps, OpenAI Codex, GitHub Copilot, Cursor, Gemini CLI, Kiro, OpenCode, Goose, Amp, Roo Code, JetBrains Junie, Factory Droid, Devin (ex-Windsurf), Mistral Vibe, OpenHands, Letta
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Security
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Attribution and licence
- Created by
- MathWorks
- Publisher
- MathWorks (Official)
- Source
- matlab/matlab-agentic-toolkit · skills-catalog/matlab-software-development/matlab-modernize-code · commit 2a7f215
- Licence
- BSD 2-Clause License (redistribution allowed)
- LICENSE (added by AutoGineer from LICENSE.md)
- ATTRIBUTION.md (written by AutoGineer)
- Synced
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