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EQN(1) General Commands Manual EQN(1) delim $$ NAME eqn, neqn, checkeq - typeset mathematics SYNOPSIS eqn [ option ... ] [ file ... ] neqn [ option ... ] [ file ... ] checkeq [ file ... ] DESCRIPTION Eqn is a troff(1) preprocessor for typesetting mathematics on a photo- typesetter, neqn on terminals. Usage is almost always eqn file ... | troff neqn file ... | nroff If no files are specified, these programs read from the standard input. Eqn prepares output for the typesetter named in the -Tdest option (Mer- genthaler Linotron 202 default, see troff(1)). When run with other preprocessor filters, eqn usually comes last. A line beginning with .EQ marks the start of an equation; the end of an equation is marked by a line beginning with .EN. Neither of these lines is altered, so they may be defined in macro packages to get cen- tering, numbering, etc. It is also possible to set two characters as `delimiters'; text between delimiters is also eqn input. Delimiters may be set to characters x and y with the option -dxy or (more com- monly) with delim xy between .EQ and .EN. Left and right delimiters may be identical. (They are customarily taken to be $font CW "$$" )$. Delimiters are turned off by All text that is neither between delim- iters nor between .EQ and .EN is passed through untouched. 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 could appear, a complicated construction enclosed in braces may be used instead. Tilde represents a full space in the output, circumflex half as much. WARNING to users of the on-line manual. Unless your terminal under- stands half-spacing, the examples below will be nearly unreadable. To get a well printed copy execute man -t eqn | lp. Subscripts and superscripts are produced with the keywords sub and sup. Thus makes $x sub i$, produces $a sub i sup 2$, and gives $e sup {x sup 2 + y sup 2}$. Fractions are made with over: yields $a over b$. sqrt makes square roots: 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 Left and right brackets, braces, etc., of the right height are made with left and right: 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: produces $pile {a above b above c}$. 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. Matrices are made with matrix: produces $matrix { lcol { x sub i above y sub 2 } ccol { 1 above 2 } }$. In addition, there is rcol for a right-justified column. Diacritical marks are made with prime, dot, dotdot, hat, tilde, bar, under, vec, dyad, and under: is $x sub 0 sup prime = f(t) bar + g(t) under$, and is $x vec = y dyad$. Sizes and font can be changed with prefix operators size n, size +-n, fat, roman, italic, bold, or 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 -pn. 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: thing replacement defines a new token called thing which will be re- placed by replacement whenever it appears thereafter. The may be any character that does not occur in Keywords like ( sum ) ( int ) ( inf ) and shorthands like (>=) (->), and ( != ) are recognized. Greek letters are spelled out in the de- sired case, as in or Mathematical words like are made Roman automati- cally. Troff(1) four-character escapes like (<=) can be used anywhere. Strings enclosed in double quotes " " are passed through untouched; this permits keywords to be entered as text, and can be used to commu- nicate with troff when all else fails. SEE ALSO troff(1), tbl(1), ms(6), eqnchar(6), doctype(1) B. W. Kernighan and L. L. Cherry, `Typesetting Mathematics--User's Guide', this manual, Volume 2 J. F. Ossanna and B. W. Kernighan, `NROFF/TROFF User's Manual', ibid. BUGS To embolden digits, parens, etc., it is necessary to quote them, as in delim off EQN(1)