17.2 eqneqn is a preprocessor designed to facilitate the typesetting of mathematical equations. Use neqn with nroff . eqn has the following commandline syntax: eqn [options ] [files ] The canonical reference for eqn is Typesetting Mathematics  User's Guide , by L.L. Cherry and B.W. Kernighan, in UNIX Programmer's Manual, Tenth Edition , Volume 2, AT&T Bell Laboratories, M.D. McIlroy and A.G. Hume editors, Holt Rinehart & Winston, 1990. This paper may be downloaded from http://cm.belllabs.com/cm/cs/doc/74/eqn.ps.gz . 17.2.1 Options
17.2.2 eqn Macros
Use the checkeq command to check for unmatched macro pairs. (Not all systems have it, though.) 17.2.3 Mathematical CharactersThe character sequences below are recognized and translated as shown:
17.2.4 Mathematical TextDigits, parentheses, brackets, punctuation marks, and the following mathematical words are printed out in roman font:
17.2.5 Greek CharactersGreek letters can be printed in uppercase or lowercase. To obtain Greek letters, simply spell them out. Some uppercase Greek letters are not supported because they can be specified by a roman equivalent (e.g, A for alpha, B for beta).
17.2.6 Diacritical Marks
Several keywords are available to mark the tops of characters. eqn
centers a mark at the correct height.
17.2.7 Keywords Recognized by eqnIn addition to character names and diacritical marks, eqn recognizes the following keywords.
17.2.8 PrecedenceIf you don't use braces, eqn performs operations in the order shown in this list, reading from left to right.
These operations group to the left:
All others group to the right. eqn defines a language for writing mathematics. Thus, there is a grammar with rules about how to group and order items within the equation. See the Bell Labs memorandum for the full story. 17.2.9 eqn ExamplesInput: .EQ delim %% .EN %sum from i=0 to inf c sup i~=~lim from {m > inf} sum from i=0 to m c sup i% .EQ delim off .EN Result: Input: .EQ x ~=~ left [ { b ~+~ sqrt {b sup 2  ~4ac} } over 2a right ] .EN  
