Jeong Dal schrieb am 29.12.2019 um 14:33:

Dear Hans,

I run the following code which is in page 24,25 luametafun.pdf.

1. adding \starttext and \stoptext, it works fine. No overlapping.

Also, functionstyle = “math” is working nicely.

2. removing \starttext and \stoptext, then functionstyle =“math” invoked an error.

3. removing \starttext, \stoptext, and functionstyle=“math”, it worked. However the caption

“x=[…]; y=[….]” is overlapped.

ConTeXt doesn't preload fonts and only when no font was set untill \starttext latin modern is used as fallback font at this point.

When you omit \starttext no font is loaded and when you use math mode (which is the case when you use funtionstyle=math) the error message appears. Another fallback in this case it to load a monospaced font in horizontal or vertical boxes which is what you set in your example when you remove \starttext.

Wolfgang