Subversion Repositories planix.SVN

.TH EQN 1

.EQ

delim $$

.EN

.SH NAME

eqn  \- typeset mathematics

.SH SYNOPSIS

.B eqn

[

.I option ...

]

[

.I file ...

]

.SH DESCRIPTION

.I Eqn

is a

.IR troff (1)

preprocessor

for typesetting mathematics

on a typesetter.

Usage is almost always

.IP

.L

eqn file ... | troff

.PP

If no files are specified, 

.I eqn

reads from the standard input.

.I Eqn

prepares output for the typesetter 

named in the

.BI -T dest

option (default

.BR -Tutf ;

see

.IR troff (1)).

When run with other preprocessor filters,

.I eqn

usually comes last.

.PP

A line beginning with

.B .EQ

marks the start of an equation;

the end of an equation

is marked by a line beginning with

.BR .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 characters

as `delimiters';

text between delimiters is also

.I eqn

input.

Delimiters may be set to characters

.I x

and

.I y

with the option

.BI -d xy

or (more commonly) with

.B delim

.I xy

between

.B .EQ

and

.BR .EN .

Left and right delimiters may be identical.

(They are customarily taken to be

$font L "$$" )$.

Delimiters are turned off by

.LR "delim off" .

All text that is neither between delimiters nor between

.B .EQ

and

.B .EN

is passed through untouched.

.PP

Tokens within

.I eqn

are separated by

spaces, tabs, newlines, braces, double quotes,

tildes or circumflexes.

Braces {} are used for grouping;

generally speaking,

anywhere a single character like

.L x

could appear, a complicated construction

enclosed in braces may be used instead.

Tilde

.L ~

represents a full space in the output,

circumflex

.L ^

half as much.

.PP

.vs 13p

Subscripts and superscripts are produced with the keywords

.B sub

and

.BR sup .

Thus

.L "x sub i" 

makes

$x sub i$, 

.L "a sub i sup 2"

produces

$a sub i sup 2$,

and

.L "e sup {x sup 2 + y sup 2}"

gives

$e sup {x sup 2 + y sup 2}$.

.PP

.B Over

makes fractions:

.L "a over b"

yields $a over b$.

.PP

.B Sqrt

produces square roots:

.L "1 over sqrt {ax sup 2 +bx+c}"

results in

$1 over sqrt {ax sup 2 +bx+c}$ .

.PP

The keywords

.B from

and

.B to

introduce lower and upper

limits on arbitrary things:

$lim from {n -> inf} sum from 0 to n x sub i$

is made with

.LR "lim from {n -> inf} sum from 0 to n x sub i" .

.PP

Left and right brackets, braces, etc., of the right height are made with

.B left

and

.BR right :

.L "left [ x sup 2 + y sup 2 over alpha right ] ~=~1"

produces

$left [ x sup 2 + y sup 2 over alpha right ] ~=~1$.

The

.B right

clause is optional.

Legal characters after 

.B left

and

.B right

are braces, brackets, bars,

.B c

and

.B f

for ceiling and floor,

and

.B

""

for nothing at all (useful for a right-side-only bracket).

.PP

Vertical piles of things are made with 

.BR pile ,

.BR lpile ,

.BR cpile ,

and

.BR rpile :

.L "pile {a above b above c}"

produces

$pile {a above b above c}$.

There can be an arbitrary number of elements in a pile.

.B lpile

left-justifies,

.B pile

and

.B cpile

center, with different vertical spacing,

and 

.B rpile

right justifies.

.PP

Matrices are made with

.BR matrix :

.L "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

.B rcol

for a right-justified column.

.PP

.vs 12p

Diacritical marks are made with

.BR prime ,

.BR dot ,

.BR dotdot ,

.BR hat ,

.BR tilde ,

.BR bar ,

.BR under ,

.BR vec ,

.BR dyad ,

and

.BR under :

.L "x sub 0 sup prime = f(t) bar + g(t) under"

is

$x sub 0 sup prime = f(t) bar + g(t) under$,

and

.L "x vec = y dyad"

is

$x vec = y dyad$.

.PP

Sizes and fonts can be changed with prefix operators

.B size 

.IR n ,

.B size

.BI ± n \f1,

.BR fat ,

.BR roman ,

.BR italic ,

.BR bold ,

or

.BR font

.IR n .

Size and fonts can be changed globally in a document by

.B gsize

.I n

and

.B gfont

.IR n ,

or by the command-line arguments

.BI -s n

and

.BI -f n\f1.

.PP

Normally subscripts and superscripts are reduced by

3 point sizes from the previous size;

this may be changed by the command-line argument

.BI -p n\f1.

.PP

Successive display arguments can be lined up.

Place

.B mark

before the desired lineup point in the first equation;

place

.B lineup

at the place that is to line up vertically in subsequent equations.

.PP

Shorthands may be defined

or existing keywords redefined with

.BR define :

.L define

.I thing

.L %

.I replacement

.L %

defines a new token called

.I thing

which will be replaced by

.I replacement

whenever it appears thereafter.

The 

.L %

may be any character that does not occur in

.LR replacement .

.PP

Keywords like 

.L sum

.EQ

( sum ),

.EN

.L int

.EQ

( int ),

.EN

.L inf

.EQ

( inf ),

.EN

and shorthands like

.L >=

.EQ

(>=),

.EN

.L ->

.EQ

(->),

.EN

and

.L !=

.EQ

( != )

.EN

are recognized.

Greek letters are spelled out in the desired case, as in

.L alpha

or

.LR GAMMA .

Mathematical words like

.LR sin ,

.LR cos ,

.L log

are made Roman automatically.

.IR Troff (1)

four-character escapes like

.L \e(lh

(\(lh) 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 communicate

with 

.I troff

when all else fails.

.SH FILES

.TF /sys/lib/troff/font/devutf

.TP

.B /sys/lib/troff/font/devutf

font descriptions for PostScript

.SH SOURCE

.B /sys/src/cmd/eqn

.SH "SEE ALSO"

.IR troff (1), 

.IR tbl (1)

.br

J. F. Ossanna and B. W. Kernighan,

``Troff User's Manual''.

.br

B. W. Kernighan and L. L. Cherry,

``Typesetting Mathematics\(emUser's Guide'', 

.I

Unix Research System Programmer's Manual,

Tenth Edition, Volume 2.

.SH BUGS

To embolden digits, parens, etc.,

it is necessary to quote them,

as in 

.LR bold\ "12.3" .

.EQ

delim off

.EN