Environment
In the Editor, you now can select a rectangular area in your code (also known as column selection or block edit) by pressing the Alt key while making a selection with the mouse. On macOS systems, use the Option key instead. Selecting and editing a rectangular area of code is useful if you want to copy or delete several columns of data, or if you want to edit multiple lines at one time.
For example, select the second column of data in A.
Type 0 to set all the selected values to
0.
To zoom in or out in the Editor, go to the View tab, and in the
Zoom section, select the 
Zoom In or 
Zoom Out button. As you zoom, MATLAB® displays the current scale in the bottom-right corner of the Editor. You
also can hold the Ctrl key and move the scroll wheel, or press
Ctrl+Plus and Ctrl+Minus. On macOS systems, use the Command key and move the scroll wheel,
or press Command+Shift+Plus and
Command+Shift+Minus.
To return to the default scale, in the View tab
Zoom section, select 
Reset Zoom. You also can press Ctrl+Alt+0
(Command+Alt+0 on macOS).
Starting in R2021b, when you write commands in the Editor, MATLAB automatically displays contextual hints for arguments, property values, and alternative syntaxes. In previous releases, MATLAB only completes names in the Editor after a Tab key press.
For example, if you want to use the size function, MATLAB automatically displays the syntax information to help you write the
command as you type.
MATLAB also automatically suggests and completes the names of functions, models, MATLAB objects, files, folders, variables, structures, graphics properties, parameters, and options.
You can disable automatic completions in the Editor and Live Editor by having
MATLAB suggest and complete names only after you press the Tab
key. To do so, on the View tab, in the Display
section, click the 
Automatic Completions button off. You also can go to the
Home tab, and in the Environment section,
click 
Preferences. Then, select Editor/Debugger > Automatic Completions and in the Suggestions and completions section,
select Show on tab.
For more information, see Check Syntax as You Type.
When debugging code in the Editor, you now can diagnose problems using inline
debugging controls. For example, to run to a specific line of code and then pause, click
the 
button to the left of the line.
To step into a file, click the 
button directly to the left of the function you want
to step into. After stepping in, click the 
button at the top of the file to run the rest of the
called function, leave the called function, and then pause.
By default, the button only appears for user-defined functions and
scripts. To show the button for MathWorks® functions as well, on the Home tab, in the
Environment section, click
Preferences. Then, select MATLAB > Editor/Debugger, and in the Debugging in the Live Editor section,
clear the Only show Step in button for user-defined functions
option.
When you step into a called function or file, the Editor displays an improved breadcrumb-style list of the functions MATLAB executed before pausing at the current line (also called the function call stack). The function call stack is shown at the top of the file and displays the functions in order, starting on the left with the first called script or function, and ending on the right with the current script or function in which MATLAB is paused.
For more information, see Debug MATLAB Code Files.
MATLAB now automatically completes parentheses and quotes when you enter code in the Editor. For example, if you type an open parenthesis in the Editor, MATLAB automatically adds the closing parenthesis. MATLAB also automatically completes comments, character vectors, strings, and parentheses split across two lines.
You also can have MATLAB automatically complete block endings. To do so, on the
Home tab, in the Environment section,
click
Preferences. Select Editor/Debugger > Automatic Completions and in the Autocoding options section, select one or
more of the Autocomplete block endings options.
To undo an automatic code completion, press Ctrl+Z or the Undo button. To disable automatic code completions, in the Editor/Debugger > Automatic Completions preferences, clear one or more of the options in the Autocoding options section.
Starting in R2021b, sections in the Editor have an improved appearance. To create a new section, go to the Editor tab and in the Section section, click the Section Break button. The new section is highlighted with a blue border, indicating that it is selected.
To maximize the space available for editing code in the Editor, you can hide the Run to Here and Code Folding margins. This minimizes the gray area to the left of your code. To hide the two margins, right-click the gray area to the left of your code and clear the Show Run to Here Margin and Show Code Folding Margin options.
As part of this change, the options for changing the appearance of code sections in the Editor have been removed. These options were previously available in the MATLAB > Colors > Programming Tools preferences, in the Section display options section.
For more information about sections in the Editor, see Create and Run Sections in Code.
Export animations to movies or animated GIFs using the new 
Export Animation button in the Live Editor animation
playback controls. The Export Animation button is not supported for animations generated
by the movie function.
For example, this code animates a line growing as it accumulates 2000 data points in
the Live Editor. When the animation is done playing, playback controls, including the
new Export Animation button, display within the figure
window.
h = animatedline;
axis([0 4*pi -1 1])
x = linspace(0,4*pi,2000);
for k = 1:length(x)
y = sin(x(k));
addpoints(h,x(k),y);
drawnow
end
For more information about creating animations, see Animation Techniques.
In R2021b, the comparison tool uses MATLAB Editor syntax highlighting. Text changes and merge choices are now easier
to understand. Changes are highlighted with strong colors. Modified lines are
highlighted and flagged with the comparison icons 
, 
, or 
. Merging line by line is straightforward, and merge
choices are flagged with the merge content icon 
.
Starting in R2021b, you no longer can save the comparison report as HTML or specify whether to show only the differences or the entire files.
The Increment Value and Run Section tool previously available in the Editor has been removed.
To increment a numeric value within a section, use controls in the Live Editor. For example, this code calculates the factorial of the variable x.
x = 5; y = factorial(x)
y = 120
5 with a numeric slider. By default, MATLAB reruns the current section when the value of the slider
changes.
For more information, see Add Interactive Controls to a Live Script.
Language and Programming
Data Analysis
Data Import and Export
Mathematics
Graphics
Create plots by passing a table directly to any of these functions: scatter, scatter3, bubblechart, bubblechart3, swarmchart, swarmchart3, polarscatter, and polarbubblechart. When you specify your data as a table, the axis labels
and the legend (if present) are automatically labeled using the table variable
names.
The objects returned by these functions have new properties to support tables.
| Property | Description |
|---|---|
| Table containing the data to plot |
| Table variables containing the x, y, and z values for Cartesian plots |
| Table variables containing the angle and radius values for polar plots |
| Table variable containing the marker size data |
| Table variable containing the marker color data |
| Table variable containing the marker transparency data |
For example, create a table with the variables "Trials" and
"Response". Pass the table to the scatter
function as the first argument, and indicate the variables you want to plot by name.
Trials = randi(10,50,1); Response = rand(50,1); t = table(Trials,Response); scatter(t,"Trials","Response")
Now, you can remove tick marks and customize tick label colors independently of other elements in the axes.
Removing Tick Marks — Remove all the tick marks from an axes, polar axes, or geographic axes object by setting the
TickDirproperty to'none'. To remove the tick marks from a specific axis, for example the x-axis, set theTickDirectionproperty of the ruler to'none'.Customizing Tick Label Colors — Customize the color of the tick labels on an axis by setting the
TickLabelColorproperty of the corresponding ruler object. You can customize tick label colors for any axes, polar axes, or geographic axes.
For example, create a bar chart, and then get the current axes. Remove the x-axis tick marks and change the color of the x-axis tick labels to red.
bar([2017 2018 2019 2020],1:4) ax = gca; ax.XAxis.TickDirection = 'none'; ax.XAxis.TickLabelColor = 'r';
Easily add additional visualizations to plots generated using the Create Plot Live Task. To add a new plot, click the Add tab at the bottom of the Live Task Panel and select the visualization and data. This Live Task combines the plot using the hold function.
The Create Plot Live Task now
supports multiple configurations of charting functions with multiple input syntaxes,
including surf and mesh. Use the
Configurations drop-down menu to select the desired
configuration.
App Building
When debugging code in App Designer, you now can diagnose problems using debugging controls in Code View. You can use the controls in the Run section of the Editor tab to run to the next breakpoint, run the next line of code, or step into or out of a function.
You can also debug your app code using inline debugging controls. For example, to run
to a specific line of code and then pause, click the button to the left of the line. To step into a
function, click the button directly to the left of the function you want
to step into. After stepping in, click the button at the top of the file to run the rest of the
called function, leave the called function, and then pause.
When you step into a called function or file, App Designer displays a breadcrumb-style list of the functions MATLAB executed before pausing at the current line (also called the function call stack). The function call stack is shown at the top of the file and displays the functions in order, starting on the left with the first called script or function, and ending on the right with the current script or function in which MATLAB is paused.
Many of the tools and shortcuts for navigating and organizing code that are available in the Live Editor can now be used in App Designer Code View. This table lists the functionality that is new to App Designer.
| Functionality | Menu Item | Keyboard Shortcut |
|---|---|---|
| Wrap comment | Right-click the comment and select Wrap
Comments, or in the Editor tab,
in the Code section, click the | Ctrl+J |
| Navigate code using bookmarks | In the Editor tab, in the Navigate section, click Bookmark. Then, select Bookmark to set or clear a bookmark on the current line, or select Previous or Next to navigate between the existing bookmarks.
| Set or clear bookmark: Ctrl+F2 |
| Move to previous bookmark: Shift+F2 | ||
| Move to next bookmark F2 | ||
| Print app code | In the Editor tab, in the File section, click Print. You can print the entire document or the current selection.
| Ctrl+P |
| Fold and expand code | In the View tab, click the buttons in the Code Folding section.
| Expand current fold: Ctrl+Shift+Period (.) |
| Collapse current fold: Ctrl+Period (.) | ||
| Expand all folds: Ctrl+Shift+Comma (,) | ||
| Collapse all folds: Ctrl+Comma (,) | ||
| Toggle display preferences | In the View tab, in the Display section, toggle line highlighting and line numbers.
| N/A |
| Duplicate line | Right-click a line and select Duplicate Line(s). | Ctrl+Shift+C |
| Insert section break | Right-click a line and select Section Break. | Ctrl+Alt+Enter, or type
%% |
| Convert text to uppercase or lowercase | Highlight the text, right-click it, and select Change Case. | Ctrl+Shift+A |
| Variable rename | When you rename a variable, App Designer gives you the option to automatically update all other instances of the variable in your code.
| Shift+Enter |
Code folding in App Designer persists even after you close and then reopen the file. In R2021a and earlier releases, when opening a file, App Designer expands all the code.
In Design View, use the zoom controls in the lower right corner
of the App Designer canvas, indicated by the 
button, to modify the canvas zoom level.
To automatically zoom to fit the entire app in the view, press Space.
Alternatively, click 
Fit to View in the Zoom section of the
View tab, or right-click on the canvas and select Zoom > Fit to View.
You can now provide help for apps that you create. Help text appears in the Command
Window when an app user calls the help function and specifies the
name of the app.
To add help text, in the Editor tab in Code
View, click 
App Help Text. Use the App Help
Text dialog box to specify the app summary and detailed explanation.
In addition, when an app user views the documentation for your app (for example, by
calling the doc function or by clicking the documentation link in
the help text for the app), the documentation page now displays additional
information:
The top of the page displays the app summary and detailed explanation.
The Methods Summary section displays the public functions. For each function, it also displays any comment that is inserted after the function definition statement.
When you apply Smart Indent to code in App Designer, the indentation change applies only to the current line. In R2021a and earlier releases, the Smart Indent option applied to the entire document.
To apply Smart Indent to the entire document, in Code View,
first select all the code (for example, by pressing Ctrl+A). Then,
apply Smart Indent by clicking the 
button in the Editor tab, or
pressing Ctrl+I.
Performance
In figures created with the uifigure function and in MATLAB
Online™, interactions with scatter plots of large data sets have the following
performance improvements:
Data tip markers track the mouse motion more closely.
3-D scatter plots are more responsive to rotation gestures.
This improvement can be seen when the axes are created with either the
axes or uiaxes function.
For example, on a Windows 10, Intel Xeon CPU E5-1650 v4 @ 3.60 GHz system, when you hover the cursor over the following sphere, the cursor changes to a crosshair more quickly, and the data tip markers track the cursor more closely. When you click and drag the cursor within the axes, the sphere rotates more quickly and tracks the cursor more closely.
f = uifigure;
ax = axes(f);
[X,Y,Z] = sphere(900);
scatter3(ax,X(:),Y(:),Z(:),[],Z(:),".")
Saving apps in App Designer after you edit an app function or property is faster in R2021b than in R2021a. The more lines of code in the app file, the greater the performance improvement becomes.
For example, on a Windows 10, Intel
Xeon W-2133 CPU @ 3.60 GHz test system, in an app containing 10,000 lines of
code, if you click Property
to create a new property and then click
Save
to save the app, you can run the updated app sooner
in R2021b than in R2021a.
The approximate save times are:
R2021a: 20 s
R2021b: 1.5 s
When you use the Comparison Tool to compare and merge changes between app code in MLAPP files, these operations have improved performance:
Loading the files into the Comparison Tool
Saving the files after merging changes
For example, if you load two apps with 5000 lines of code into the Comparison Tool by
clicking Compare
in the App Designer toolstrip, you can compare and
merge the files sooner in R2021b than in R2021a.
The approximate loading times are:
R2021a: 13 s
R2021b: 8 s
Also, if you use the Comparison Tool to merge changes between two apps with 5000 lines
of code (for example, by clicking Merge Mode
, merging the changes, and then clicking
Save Result
), you can compare the saved files sooner in R2021b
than in R2021a.
The approximate save times are:
R2021a: 24 s
R2021b: 8 s
Both of these operations were timed on a Windows 10, Intel Xeon W-2133 CPU @ 3.60 GHz test system.
The performance when you resize apps containing a grid layout manager created using
the uigridlayout function has improved when both of these conditions hold:
The grid layout manager contains a component with a
WordWrapvalue of'on'.The row and column containing the component with word wrap have a
RowHeightof'fit'and aColumnWidththat is resizable, such as'1x'.
For example, on a Windows 10, Intel Xeon CPU E5-1650 v4 @ 3.60 GHz test system, if you create 100 labels with wrapping text in a grid layout manager with fit height rows and resizable columns, and then resize the figure window by dragging the corner of the figure, the label text adjusts to fit the size of the figure almost immediately. In R2021a, there is a delay of about 2 seconds before the text adjusts.
f = uifigure;
g = uigridlayout(f);
g.ColumnWidth = {'1x'};
numrows = 100;
g.RowHeight = repmat({'fit'},numrows,1);
for row = 1:numrows
c = uilabel(g);
c.Text = ['Lorem ipsum dolor sit amet, consectetur adipiscing elit,' ...
' sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.'];
c.WordWrap = 'on';
end