12.  Symbols, Special Names, Greek

      EQN knows some mathematical symbols, some mathematical names, and the Greek alphabet. For example, x=2 pi int sin ( omega t)dt
produces

Here the spaces in the input are necessary to tell EQN that int, pi, sin and omega are separate entities that should get special treatment. The sin, digit 2, and parentheses are set in roman type instead of italic; pi and omega are made Greek; and int becomes the integral sign.

      When in doubt, leave spaces around separate parts of the input. A very common error is to type f(pi) without leaving spaces on both sides of the pi. As a result, EQN does not recognize pi as a special word, and it appears as instead of .

      A complete list of EQN names appears in section 23. Knowledgeable users can also use TROFF four-character names for anything EQN doesn't know about, like \(bs for the Bell System sign \(bs.