\lVert and \rVert are not rendered on '9.7.0.1190202 (R2019b)', Ubuntu 18.04

This line

xlabel('$\lVert x \rVert$', 'Interpreter', 'latex')

triggers this message

Warning: Error updating Text.

String scalar or character vector must have valid interpreter syntax:

$\lVert x \rVert$

and then label is rendered as "$\lVert x \rVert$", whithout the latex interpretation. \vert is rendered correctly.

Answer 1

[Walter Roberson]

Those are amsmath and that package is not included in MATLAB latex.

[Carlos Mendoza]

Hard to believe that a pretty standard LaTeX package is not supported by Matlab. Where in the official documentation is that stated? I don't like playing guessing games. They should clearly state what LaTeX packages they support.

[Walter Roberson]

That's easy: they do not support any LaTeX packages. No packages are automatically \usepackage on your behalf, and you cannot \usepackage yourself.

[Carlos Mendoza]

In the absence of an answer from the Staff and a clear statement on the official Matlab documentation, I would take this last comment of yours as the answer to my question :). Thanks.

[Walter Roberson]

There are very few references to \usepackage in the documentation.

One of them could be read very broadly as hinting that possibly two packages are automatically included.

https://www.mathworks.com/help/matlab/matlab_prog/marking-up-matlab-comments-for-publishing.html#btga6k2-3

Notice the autogenerated latex has \usepackage{graphicx} \usepackage{color} even though the user did not put those in. That hints that maybe those packages are already included by Mathworks.

But in practice, I have never been able to use the color definition facility of the color package... as if the package is in fact not included.