What’s New and Migrating Older Code

MathWorks ships two releases a year, named after the year and a letter: an "a" release in spring (March to May) and a "b" release in September. R2026b was announced on 2026-09-28. Release notes are published for every release, and the current documentation carries a note such as "Introduced in R2019b" on the reference page of a function or feature. That note is the most reliable way to date a feature. When this page says "documented", a current R2026b page states the release; when it says "release notes", the entry comes from the release notes. Three rows come from secondary sources or from general knowledge and are marked as such, because the current documentation does not state them.

Compatibility works in two directions. Code written for an older release almost always still runs, because MathWorks removes functionality slowly: a function is first listed as "not recommended", often for many releases, then "to be removed", then removed. Code written with a newer feature does not run on an older release, so a .m file that uses an arguments block fails on R2018b. The reference pages show the status in the title, for example "(Not recommended)", "(To be removed)" or "(Removed)".

The table lists the base-MATLAB changes that matter to a learner of the language. The last column says where this section explains the feature. The same table, with a "Status" column that records how each row was checked, is in the section overview, under Version baseline.

Three rows deserve a caution, because the current documentation does not confirm them. The dot notation for graphics objects is attributed to R2014b by the issue’s checklist; the current documentation confirms the histogram function in R2014b but not the dot notation itself. Double-quoted string literals in R2017a rest on MathWorks Answers and a third-party release review (nhigham.com). Local functions in scripts are attributed to R2016b, but the current page only says that before R2024a they had to be defined at the end of the file. For those three, read "about this release" rather than "exactly this release".

A correction worth making explicit, because summaries get it wrong: Python 3.14 was added and Python 3.9 dropped in R2026b, not in R2026a. The R2026a release notes add Python 3.13; the R2026b notes add 3.14 and discontinue 3.9. The page Versions of Python Compatible with MATLAB Products by Release lists R2026a as 3.9 to 3.13 and R2026b as 3.10 to 3.14.

The release notes page has one section per release, from R2026b downwards, so it is the link for every row of R2024b and later; the archived per-release pages of older releases are rendered in the browser by scripts and were not usable as stable links, which is why the older rows cite the reference pages instead. Sources: MATLAB release notes, the same notes as Markdown, and the "Introduced in" notes on arguments, pattern and mustBeBetween.

The same changes, as a picture. Each entry is a headline, not the whole list.

Each row is a form that older material teaches and the form this section uses. "Still runs" means the old form works in R2026b; it does not mean it is recommended. The first column names the book chapters where the older form appears, because the books are the reason the table exists.

In the "Since" column, the dates that also appear in the version-baseline table are checked as described there. The others (R2008b for the symbolic engine, R2011a for rng, R2012a for integral, R2014b for datetime, webread and audioread, R2016a for the live editor and fplot with function handles, R2018a for the interleaved-complex API) come from general knowledge of the release history and were not re-checked on the current pages. The point of these rows is the direction of travel, not the exact release.

Old and new forms that Octave also accepts can be compared directly. Octave 11.3.0 was used for this run, and its output layout differs slightly from MATLAB’s (MATLAB prints size headers such as 2×3):

Octave 11.3.0 output:

The two forms agree. The rest of the table (string arrays, dictionary, datetime, arguments, rng details) is MATLAB behaviour that Octave 11.3.0 does not reproduce, so no output is shown for it; the GNU Octave Compatibility page records which of these names exist in Octave.

The table lists what the section mentions as gone or going. "Errors" means the call fails; "Still runs" means it works but is marked for removal.

The deprecation statuses come from the page titles on the current reference ("(Removed)", "(To be removed)", "(Not recommended)") and from the release notes. A function that is not recommended is not the same as removed: bsxfun, containers.Map, urlread, quad, hist and strmatch all still run. Prefer the replacement in new code, and use the Code Compatibility Analyzer (next section) to find the others in an existing code base.

Sources: guide (Removed), info (Removed), whatsnew (Removed), serial (To be removed), serialport, mustBeInRange (Not recommended).

Before moving code to a newer release, ask MATLAB what it thinks will break. The Code Compatibility Analyzer scans your files and lists, in tabular form, the compatibility issues it can detect, with an instruction for each. Its report groups the findings by what will happen: functionality that has been removed, functionality that has changed behaviour, unsupported or undocumented functionality that may cause errors, functionality that will be removed or will change behaviour in a later release, and new functionality that might improve the code. The recommended order is to fix the syntax errors first, because they stop the analysis from being reliable, then the removed functionality, then the rest.

These calls were not run here: R2026b is not installed on the machine that produced these pages, and Octave has no such function. The syntaxes codeCompatibilityReport(names), codeCompatibilityReport(___,'IncludeSubfolders',tf) and codeCompatibilityReport(cca) are those on the function’s reference page; analyzeCodeCompatibility and codeCompatibilityAnalyzer are named on the Analyzer’s topic page, which says that the Analyzer can also be opened from the Apps tab. The Code Analyzer itself, and codeIssues, are covered on Code Analyzer and Code Quality.

Source: MATLAB documentation: MATLAB Code Compatibility Analyzer, codeCompatibilityReport

When you modernise a script or a small library, work through the changes in this order. The order puts the mechanical, low-risk changes first.

Removed functions fail at the call, not when the file is loaded: a call to wavread in current MATLAB stops with "Unrecognized function or variable 'wavread'.", identifier MATLAB:UndefinedFunction, so only code paths that are actually run, or the Code Compatibility Analyzer, reveal them.

Step 5 is the main compatibility trap: code that uses implicit expansion does not run on R2016a or earlier, where [1 2 3] + [1; 2] stopped with "Matrix dimensions must agree." (identifier MATLAB:dimagree); current releases expand it to a 2-by-3 matrix and keep an error, "Arrays have incompatible sizes for this operation." (identifier MATLAB:sizeDimensionsMustMatch), for sizes that really do not match. If you maintain code that must support old releases, keep the older forms and say so in a comment.

The table above is the collected answer. The shortest summary: the primer teaches the MATLAB of 2010, with a Java desktop, a Help browser, cell publishing, GUIDE and bsxfun; the 2021 mathematics volume keeps the 1990s habits of its source material (numeric graphics handles, hist, quad) and its listings were corrupted in conversion, so this section does not reproduce them. Everything those books teach about arrays, indexing, control flow, functions, classdef and the numerical functions remains correct. The things that changed are the surface: the desktop, the text and date types, argument checking, the graphics handle type, the names package and toolbox, and the tools around the language (the Code Analyzer, live scripts, buildtool, the package manager).