delim $$ NAME eqn - typeset mathematics SYNOPSIS eqn [ file ] ... DESCRIPTION Eqn is a troff (I) preprocessor for typesetting mathematics on the Graphics Systems phototypesetter. Usage is almost always 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 begin- ning with ``.EN''. Neither of these lines is altered or defined by eqn, so you can define them yourself to get cen- tering, numbering, etc. All other lines are treated as com- ments, 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 equation. 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 is $a over b$ and 1 over sqrt {ax sup 2 +bx+c} is $1 over sqrt {ax sup 2 +bx+c}$ . sqrt makes square roots. 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. 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-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 $x dot = f(t) bar$. Default sizes and fonts can be changed with size n and various of roman, italic, and bold. Keywords like sum ( sum ) int ( int ) inf ( inf ) and short- hands 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 1 () can be used anywhere. Strings enclosed in double quotes "..." are passed through untouched. SEE ALSO A System for Typesetting Mathematics (Computer Science Tech- nical Report #17, Bell Laboratories, 1974.) TROFF Users' Manual (internal memorandum) TROFF Made Trivial (internal memorandum) troff (I), neqn (I) BUGS 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 gen- eral. 2