How do I get bold formatted subscript mathematical expressions in MATLAB using LaTeX?

I want to format the variable as given as an axis label for a figure using the the latex interpreter: Both, g and R, should be italic, but R should be subscript and bold additionally. In the corresponding document, that the figure is for, I formatted it as $g_{\boldsymbol{R}}$, however this does not seem to work here. So far, I found a very similar question, yet the accepted answer does not use a subscript and I do not seem to get the described math mode switching to work. Any help, getting the math mode switching to work, or a totally different approach to format the label as intended, is appreciated. Thanks in advance!

Answer 1

[Torsten]

x = 0:10;
y = x;
plot(x,y)
xlabel('$g_{\mathbf{\mathit{R}}}$','interpreter','latex')

[Simon]

Here, the R is upright, but it should be italic.

[Torsten]

Changed it.

[Simon]

Now, the R is italic, but not bold anymore, in R2022a at least. The commands for formatting characters bold and italic show the same behavior of deactivating each other, that I faced before posting the question.

Answer 2

[Star Strider]

Using

g_{\it\textbf{R}}

works here using tthe LaTeX interpreter (Σ button in the top toolbar) --

The 'R' actually is subscripted. Were it not, it would appear as --

Using it as an axis label --

figure
xlabel('$g_{\it\textbf{R}}$', Interpreter='LaTeX')

.

[Simon]

Here, the R is upright, but it should be italic, in R2022a at least. The commands for formatting characters bold and italic show the same behavior of deactivating each other, that I faced before posting the question.

[Star Strider]

It works correctly in R2024b (apparently the online Run application has not upgraded to R2025a yet) --

figure
xlabel('$g_{\it\textbf{R}}$', Interpreter='LaTeX', FontSize=26)

●

Here, the 'R' is bold, italic, and subscripted. (The code is the same as before, with only the FontSize name-value pair added for clarity.

If it is not working this way in your R2022a installation, be sure you have downloaded and insatalled all the updates. If this was a bug, it could have been fixed.

.

[Simon]

I updated it, yet, the issue still occurs. Could you think of a workaround or have a look at how to adapt this approach? I do not really want to change the version of my installation for this project.

[Star Strider]

If the approach that you reference works for you, then go for it. It appears to work, at least in the referenced releases.

Alternatively, you can plot here and then upload the plot as an image --

figure
xlabel('$g_{\it\textbf{R}}$', Interpreter='LaTeX', FontSize=26)

savefig(gcf,'ItalicBoldSubscript.fig')

figfiles = dir('*.fig')

figfiles = struct with fields:
       name: 'ItalicBoldSubscript.fig'
     folder: '/users/mss.system.pzgkb'
       date: '20-Aug-2025 16:59:44'
      bytes: 5901
      isdir: 0
    datenum: 7.3985e+05

which('ItalicBoldSubscript.fig')

/users/mss.system.pzgkb/ItalicBoldSubscript.fig

openfig('ItalicBoldSubscript');

There does not appear to be a way to save it to MATLAB Drive (at lest that I can find, if that were possible you could then export it through MATLAB Online), so the easiest way to do it would probably be to copy it by right-clicking on it and then saving it appropriately, or taking a screenshot of it.

.