LaTex的几种数学符号字体以及相关说明
\mathrm
is the normal upright Roman font
\mathnormal
is the normal math italic font: $\mathnormal{a}$
and $a$
give the same result
\mathcal
is the special calligraphic font for uppercase letters only
\mathbf
gives upright Roman boldface letters
\mathsf
gives upright sans serif letters
\mathit
gives text italic letters: $different\ne\mathit{different}$
\mathtt
gives upright letters from the typewriter type font
\mathbb