有没有一些输入法可以轻松输入数学符号UTF8字符（例如U+2200 适合所有人 ∀,U+2203 存在 ∃, U+2208 元素 ε,U+2190 向左箭头 ←， ETC...）？
I would like to type easily these characters in some <textarea> in Firefox (38 or 42) on Debian/Linux/x86_64 under xfce4 or Gnome (and I want to avoid Javascript tricks for that). I am currently copy/pasting them from some CharacterMap application, which is uneasy.
The answers to this related question requires some ad-hoc configuration; I am asking for a standard input method.
答案1
Try this: press ctrl-shft-U and then type the 4-digit code. This works on my Gnome shell desktop (Fedora 20, though). For example, when I type ctl-shft-U 2203 and then hit the space bar, it gives me ∃ . See http://library.gnome.org/users/gnome-help/stable/tips-specialchars.html.en