Special characters are all of those symbols and glyphs that are not available to you by way of direct keyboard input, and in modern operating systems with full Unicode character palettes, there are thousands of them. Your Mac comes with numerous type faces, many of which are fonts for specific languages, so they contain vast arrays of unique characters. In addition, there are numerous symbols, technical and otherwise, that are included with OS X.
To access these characters, you can sometimes use various combinations of modifier keys on your keyboard, such as Option-z to enter an Omega symbol on a U.S. English keyboard layout. To see all of these options, you can enable and open the system’s keyboard viewer panel:
- Go to the Keyboard system preferences.
- Check the “Show Keyboard & Character Viewers in Menu Bar” option in the Keyboard tab.
- Open the new input sources menu that appears in the status menus.
- Choose the Keyboard Viewer option.
The keyboard viewer is limited to showing what can be typed with the keyboard, so you can use the Character Viewer option in this same menu to open the system’s character palette, which will allow you to browse through every available character on the system, including picking from font variants that are available.
To get the most out of the Character Viewer, click the gear menu at the top-left and then choose Customize List, where you can enable a number of additional categories such as Braille, pictographs, musical symbols, math symbols, and more. To use a symbol that you like, you can drag and drop it, or double-click it to enter it a the location of your cursor.
While the Character Viewer is available in the Input menu, you can also access it by pressing Option-Command-T in most programs.
How to type the x bar statistical mean (statistical average) that looks like this (I am copy/pasting it): x̅.
The “overline” in x̅ is not as common as other diacritical marks in foreign languages, so unlike, say, ˜, ´,` ˆ, or ¨, there is no trivial way of inserting it. (For those who don’t know, ˜ is option-n, ´ is option-e, ` is option-`, ˆ is option-i, and ¨ is option-u). Furthermore, you want to insert it over a letter (x) for which it is even less common to have such diacriticals, so even things like ẍ or x́ are not easy to type.
Having said that, I’ll tell you two ways to get the overline. If you want to use it very rarely, the best way is to enable the “Code Tables: Unicode” section in the Character Viewer (follow the instructions for the “gear” at the end of the article). Then select Unicode from the list on the left, navigate to the section Combining Diacritical Marks (hint: starts at 0300). Now, on the text you are writing type the “x”, and then double click on the overline entry in the table (row 0300, column 5). You’ll get the overline drawn over the x: x̅.
Now that you know that the diacritical is called “combining overline” you can get rapidly to it by typing in the search box “overline” (or better yet “combining” to get more combining diacriticals).
For the second method, suppose that you regularly use some of these diacriticals a lot because you write a lot of math, enough for you to learn their hexadecimal unicode codes (in the case of ̅ it’s 0305). You’ll need to activate the Unicode Hex Input item of the Input menu: In Mavericks, go to the Keyboard system preferences, Input Sources tab, + to add to the list of keyboards, category “Others” (at the end of the list), add Unicode Hex Input.
Now that it’s in the menu, choose Unicode Hex Input. Type “x” (or any other letter) followed by option-0305 (that is: keep “option” pressed while you type “0305”), and you’ll get x̅.
With either method, you can sometimes use more than one combining diacritical: “x option-20d1 option-20ed” gives you x⃭⃑ (an “x” with a right harpoon on top and a left harpoon bellow).
When it comes to typing special characters, the luxury model of applications is PopChar. I often amaze and mystify my friends with my Emoji typing skills. It’s all thanks to PopChar.