Dear Wolfgang,

Now, I understand why the error messages “\texfont0 is undefined”, “ you used the started character from an undefined font family.” are appeared.

Thank you for your clear explanation.

Best regards,

Dalyoung


>> 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.