EQN(I)                       2/22/74                       EQN(I)


     eqn  -  typeset mathematics


     eqn [ file ] ...


     Eqn is a troff (I) preprocessor for typesetting  mathematics

     on  the  Graphics  Systems phototypesetter.  Usage is almost


             eqn file ... | troff

     If no files are  specified,  eqn  reads  from  the  standard

     input.   A line beginning with ``.EQ'' marks the start of an

     equation; the end  of  an  equation  is  marked  by  a  line

     beginning  with  ``.EN''.  Neither of these lines is altered

     or defined by eqn, so you can define them  yourself  to  get

     centering,  numbering,  etc.  All other lines are treated as

     comments, and passed through untouched.

     Spaces, tabs, newlines, braces,  double  quotes,  tilde  and

     circumflex  are the only delimiters.  Braces ``{}'' are used

     for grouping.  Use tildes ``~'' to get extra  spaces  in  an


     Subscripts and superscripts are produced with  the  keywords

     sub  and sup.  Thus x sub i makes xi, a sub i sup 2 produces
      2                                         2  2
     ai, and e sup {x sup 2 + y sup 2} gives  ex +y .   Fractions
     are made with over.  a over b is _ and 1 over sqrt {ax sup 2
     +bx+c} is   ________ .  sqrt makes square roots.

     The keywords from and to introduce lower and upper limits on

     arbitrary  things:   lim Σxi is made with lim from {n-> inf}

     sum from 0 to n x sub i.  Left and right  brackets,  braces,

     etc., of the right height are made with left and right: left

     [ x sup 2 + y  sup  2  over  alpha  right  ]  ~=~1  produces
     |      |
     |x2+ __| = 1.  The right clause is optional.
     |      |

     Vertical piles of things are made with pile,  lpile,  cpile,

     and  rpile:  pile {a above b above c} produces b.  There can

     be an arbitrary number of elements in a pile.   lpile  left-

     justifies,  pile  and  cpile center, with different vertical

     spacing, and rpile right justifies.

     Diacritical marks are made with dot, dotdot, hat, bar: x dot
                       . ____
     =  f(t)  bar  is  x=f(t).   Default  sizes  and fonts can be

     changed with size n and various of roman, italic, and bold.

     Keywords like sum (Σ) int (∫) inf (oo) and  shorthands  like

     >=  (>)  ->  (->),  != (≠), are recognized.  Spell out Greek

     letters  in  the  desired  case,   as   in   alpha,   GAMMA.

     Mathematical  words  like  sin,  cos,  log  are  made  Roman

     automatically.  Troff (I) four-character escapes  like  \(bs

     (o) can be used anywhere.  Strings enclosed in double quotes

     "..."  are passed through untouched.


     A  System  for  Typesetting  Mathematics  (Computer  Science

     Technical Report #17, Bell Laboratories, 1974.)

     TROFF Users' Manual (internal memorandum)

     TROFF Made Trivial (internal memorandum)

     troff (I), neqn (I)


     Undoubtedly.  Watch out for small or  large  point  sizes  -

     it's  tuned  too well for size 10.  Be cautious if inserting

     horizontal  or  vertical  motions,  and  of  backslashes  in