delim $$ NAME eqn - typeset mathematics SYNOPSISeqn[ file ] ... DESCRIPTIONEqnis a troff(I) preprocessor for typesetting mathematics on the Graphics Systems phototypesetter. Usage is almost always eqn file ... | troff If no files are specified,eqnreads 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 begin- ning with ``.EN''. Neither of these lines is altered or de- fined byeqn,so you can define them yourself to get center- ing, 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 keywordssubandsup.Thusx sub imakes $x sub i$,a sub i sup 2produces $a sub i sup 2$, ande sup {x sup 2 + y sup 2}gives $e sup {x sup 2 + y sup 2}$. Fractions are made withover. a over bis $a over b$ and1 over sqrt {ax sup 2+bx+c}is $1 over sqrt {ax sup 2 +bx+c}$ .sqrtmakes square roots. The keywordsfromandtointroduce lower and upper limits on arbitrary things: $lim from {n-> inf} sum from 0 to n x sub i$ is made withlim from {n-> inf} sum from 0 to n x sub i.Left and right brackets, braces, etc., of the right height are made withleftandright: left [ x sup 2 + y sup 2 overalpha right ] ~=~1produces $left [ x sup 2 + y sup 2 over alpha right ] ~=~1$. Therightclause is optional. Vertical piles of things are made withpile, lpile, cpile,andrpile: pile {a above b above c}produces $pile {a above b above c}$. There can be an arbitrary number of elements in a pile.lpileleft-justifies,pileandcpilecenter, with different vertical spacing, andrpileright justifies. Diacritical marks are made withdot, dotdot, hat, bar: x dot= f(t) baris $x dot = f(t) bar$. Default sizes and fonts can be changed withsize nand various ofroman, italic,andbold.Keywords likesum( sum )int( int )inf( inf ) and short- hands like >= (>=) -> (->), != ( != ), are recognized. Spell out Greek letters in the desired case, as inalpha,GAMMA.Mathematical words like sin, cos, log are made Roman automatically. Troff(I) four-character escapes like \(ci (O) can be used anywhere. Strings enclosed in double quotes - 1 - EQN(I) 2/22/74 EQN(I) "..." 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 gener- al. delim off - 2 -