term% ls -F
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term% cat index.txt
EQN(1)                      General Commands Manual                     EQN(1)

delim $$

       eqn, neqn, checkeq  -  typeset mathematics

       eqn [ -dxy ] [ -pn ] [ -sn ] [ -fn ] [ file ] ...
       checkeq [ file ] ...

       Eqn is a troff(1) preprocessor for typesetting mathematics on a Graphic
       Systems phototypesetter, neqn on terminals.  Usage is almost always

            eqn file ... | troff
            neqn file ... | nroff

       If no files are specified, these programs reads from the  standard  in‐
       put.   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, so they may be defined in macro packages to
       get centering, numbering, etc.  It is also possible to set two  charac‐
       ters  as  `delimiters';  subsequent  text  between  delimiters  is also
       treated as eqn input.  Delimiters may be set to characters x and y with
       the  command-line  argument -dxy or (more commonly) with `delim xy' be‐
       tween .EQ and .EN.  The left and right  delimiters  may  be  identical.
       Delimiters are turned off by `delim off'.  All text that is neither be‐
       tween delimiters nor between .EQ and .EN is passed through untouched.

       The program  checkeq  reports  missing  or  unbalanced  delimiters  and
       .EQ/.EN pairs.

       Tokens within eqn are separated by spaces, tabs, newlines, braces, dou‐
       ble quotes, tildes or circumflexes.  Braces {} are used  for  grouping;
       generally  speaking, anywhere a single character like x could appear, a
       complicated construction enclosed in braces may be used instead.  Tilde
       ~ represents a full space in the output, circumflex ^ half as much.

       Subscripts and superscripts are produced with the keywords sub and sup.
       Thus x sub i makes $x sub i$, a sub i sup 2 produces $a sub i  sup  2$,
       and e sup {x sup 2 + y sup 2} gives $e sup {x sup 2 + y sup 2}$.

       Fractions are made with over: a over b yields $a over b$.

       sqrt  makes  square  roots:  1 over sqrt {ax sup 2 +bx+c} results in $1
       over sqrt {ax sup 2 +bx+c}$ .

       The keywords from and to introduce lower and upper limits on  arbitrary
       things:  $lim  from {n-> inf} sum from 0 to n x sub i$ 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 $left [ x sup 2 + y sup 2 over alpha right ] ~=~1$.  The right
       clause  is optional.  Legal characters after left and right are braces,
       brackets, bars, c and f for ceiling and floor, and ""  for  nothing  at
       all (useful for a right-side-only bracket).

       Vertical  piles  of things are made with pile, lpile, cpile, and rpile:
       pile {a above b above c} produces $pile {a above b  above  c}$.   There
       can  be  an  arbitrary number of elements in a pile.  lpile left-justi‐
       fies, pile and cpile center, with different vertical spacing, and rpile
       right justifies.

       Matrices  are made with matrix: matrix { lcol { x sub i above y sub 2 }
       ccol { 1 above 2 } } produces $matrix { lcol { x sub i above y sub 2  }
       ccol  {  1 above 2 } }$.  In addition, there is rcol for a right-justi‐
       fied column.

       Diacritical marks are made with dot,  dotdot,  hat,  tilde,  bar,  vec,
       dyad,  and  under: x dot = f(t) bar is $x dot = f(t) bar$, y dotdot bar
       ~=~ n under is $y dotdot bar ~=~ n under$, and x vec ~=~ y dyad  is  $x
       vec ~=~ y dyad$.

       Sizes  and  font  can be changed with size n or size ±n, roman, italic,
       bold, and font n.  Size and fonts can be changed globally in a document
       by gsize n and gfont n, or by the command-line arguments -sn and -fn.

       Normally  subscripts and superscripts are reduced by 3 point sizes from
       the previous size; this may be changed  by  the  command-line  argument

       Successive  display  arguments  can be lined up.  Place mark before the
       desired lineup point in the first equation; place lineup at  the  place
       that is to line up vertically in subsequent equations.

       Shorthands  may  be defined or existing keywords redefined with define:
       define thing % replacement % defines a new  token  called  thing  which
       will  be replaced by replacement whenever it appears thereafter.  The %
       may be any character that does not occur in replacement.

       Keywords like sum ( sum ) int ( int ) inf ( inf ) and  shorthands  like
       >=  (>=)  ->  (->),  and  !=  ( != ) are recognized.  Greek letters are
       spelled out in the desired case, as in alpha  or  GAMMA.   Mathematical
       words  like sin, cos, log are made Roman automatically.  Troff(1) four-
       character escapes like \(bs () can be used anywhere.  Strings  enclosed
       in double quotes "..."  are passed through untouched; this permits key‐
       words to be entered as text, and can be used to communicate with  troff
       when all else fails.

       troff(1), tbl(1), ms(7), eqnchar(7)
       B. W. Kernighan and L. L. Cherry, Typesetting Mathematics—User's Guide
       J. F. Ossanna, NROFF/TROFF User's Manual

       To  embolden digits, parens, etc., it is necessary to quote them, as in
       `bold "12.3"'.

                                    2/22/74                             EQN(1)