I'm using pdflatex with book document class, and using the Sitx2 package, but when compiling a line with a math environment containing a \boldymbol command I get the error:

LaTex Font Warning: Font shape 'LS2/stix2ex/b/n' in size <10> not available
(Font)              Font shape 'LS2/stix2ex/m/n' tried instead on input line 52

Checking the Stix2 package manual (version 2.0.2), I see there are math alphabets (Chapter 4) which are not included by default: "TEX allows only 16 math alphabets to be used simultaneously, so not all of these alphabets can be used in one document. When the stix2 package is loaded, 12 math groups are allocated, with the 11 math alphabets that are marked above available by default, which leaves room for 4 other math groups to be allocated on demand when any of the other alphabets is used."

Question: how do I load (allocate) the alphabet required for \boldsymbol command? I suppose it would be the \mathbfit alphabet? Thanks.

EDIT Clarifying further, at request from comments: I need to load one of the alphabets of stix2 (Ch.4, as mentioned, not all are loaded by default). What is the specific alphabet I need to load to make \boldsymbol work, and how do I do it?

  • Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking.
    – Community Bot
    Oct 6, 2021 at 15:01
  • stix2 does not provide bold versions of all symbols (any that are marked with a * in the stix2 package manual) (the reference to math alphabets is not directly related to \boldsymbol which requires \boldmath support) Oct 6, 2021 at 15:14
  • Note that that warning just means that not all symbols provided by stix is available in bold and the non bold symbol will be used in those cases. You get the warning from usiong \boldmath even if it does not affect the symbols actually used in the document. As always a complete small document showing the problem would make it easier to answer. Oct 6, 2021 at 15:16
  • Thanks for the reply! In the document, I get a bold italic math letter, but I wasn't sure if that was the correct one, so you're telling me I can just ignore the warnings?
    – Arc
    Oct 6, 2021 at 15:20
  • we have no idea whether or not the warnings apply in your case as you have given no information but if you want a math italic letter you should not be using \boldsymbol at all use the bold math italic alphabet, \mathbfit the warning is telling you that an extension font for large symbols is not available in bold. Oct 6, 2021 at 15:44

1 Answer 1


The warning you show is not related to any symbols in the document it is warning at the point that the math fonts are swiched with \boldmath (used internally by \boldsymbol) that not all the fonts, are available in bold.

However stix2, being derived from the OpenType Math layout has many bold letters in the normal math version and so does not require use of \boldsymbol in most cases. The math alphabet \mathbfit{ABC} will give bold math italic without switching versions.

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