1EQN(1) General Commands Manual EQN(1)
2
6 eqn - format equations for troff or MathML
7
9 eqn [-rvCNR] [-d xy] [-T name] [-M dir] [-f F] [-s n] [-p n] [-m n]
10 [files...]
11
13 This manual page describes the GNU version of eqn, which is part of the
14 groff document formatting system. eqn compiles descriptions of equa‐
15 tions embedded within troff input files into commands that are under‐
16 stood by troff. Normally, it should be invoked using the -e option of
17 groff. The syntax is quite compatible with Unix eqn. The output of
18 GNU eqn cannot be processed with Unix troff; it must be processed with
19 GNU troff. If no files are given on the command line, the standard
20 input is read. A filename of - causes the standard input to be read.
21 eqn searches for the file eqnrc in the directories given with the -M
23 option first, then in /etc/groff/site-tmac, /etc/groff/site-tmac, and
24 finally in the standard macro directory /usr/share/groff/1.22.2/tmac.
25 If it exists, eqn processes it before the other input files. The -R
26 option prevents this.
27 GNU eqn does not provide the functionality of neqn: it does not support
29 low-resolution, typewriter-like devices (although it may work ade‐
30 quately for very simple input).
31
33 It is possible to have whitespace between a command line option and its
34 parameter.
35 -dxy Specify delimiters x and y for the left and right end, respec‐
37 tively, of in-line equations. Any delim statements in the
38 source file overrides this.
39 -C Recognize .EQ and .EN even when followed by a character other
41 than space or newline. Also, the statement `delim on' is not
42 handled specially.
43 -N Don't allow newlines within delimiters. This option allows eqn
45 to recover better from missing closing delimiters.
46 -v Print the version number.
48 -r Only one size reduction.
50 -mn The minimum point-size is n. eqn does not reduce the size of
52 subscripts or superscripts to a smaller size than n.
53 -Tname The output is for device name. Normally, the only effect of
55 this is to define a macro name with a value of 1; eqnrc uses
56 this to provide definitions appropriate for the output device.
57 However, if the specified device is “MathML”, the output is
58 MathML markup rather than troff commands, and eqnrc is not
59 loaded at all. The default output device is ps.
60 -Mdir Search dir for eqnrc before the default directories.
62 -R Don't load eqnrc.
64 -fF This is equivalent to a gfont F command.
66 -sn This is equivalent to a gsize n command. This option is depre‐
68 cated. eqn normally sets equations at whatever the current
69 point size is when the equation is encountered.
70 -pn This says that subscripts and superscripts should be n points
72 smaller than the surrounding text. This option is deprecated.
73 Normally eqn sets subscripts and superscripts at 70% of the size
74 of the surrounding text.
75
77 Only the differences between GNU eqn and Unix eqn are described here.
78 GNU eqn emits Presentation MathML output when invoked with the
80 -T MathML option.
81 GNU eqn sets the input token "..." as three periods or low dots,
83 rather than the three centered dots of classic eqn. To get three cen‐
84 tered dots, write cdots or cdot cdot cdot.
85 Most of the new features of the GNU eqn input language are based on
87 TeX. There are some references to the differences between TeX and GNU
88 eqn below; these may safely be ignored if you do not know TeX.
89 Controlling delimiters
91 If not in compatibility mode, eqn recognizes
92 delim on
94 to restore the delimiters which have been previously disabled with a
96 call to `delim off'. If delimiters haven't been specified, the call
97 has no effect.
98 Automatic spacing
100 eqn gives each component of an equation a type, and adjusts the spacing
101 between components using that type. Possible types are:
102 ordinary an ordinary character such as `1' or `x';
104 operator a large operator such as `Σ';
106 binary a binary operator such as `+';
108 relation a relation such as `=';
110 opening a opening bracket such as `(';
112 closing a closing bracket such as `)';
114 punctuation a punctuation character such as `,';
116 inner a subformula contained within brackets;
118 suppress spacing that suppresses automatic spacing adjust‐
120 ment.
121 Components of an equation get a type in one of two ways.
123 type t e
125 This yields an equation component that contains e but that has
126 type t, where t is one of the types mentioned above. For exam‐
127 ple, times is defined as
128 type "binary" \(mu
130 The name of the type doesn't have to be quoted, but quoting pro‐
132 tects from macro expansion.
133 chartype t text
135 Unquoted groups of characters are split up into individual char‐
136 acters, and the type of each character is looked up; this
137 changes the type that is stored for each character; it says that
138 the characters in text from now on have type t. For example,
139 chartype "punctuation" .,;:
141 would make the characters `.,;:' have type punctuation whenever
143 they subsequently appeared in an equation. The type t can also
144 be letter or digit; in these cases chartype changes the font
145 type of the characters. See the Fonts subsection.
146 New primitives
148 big e Enlarges the expression it modifies; intended to have semantics
149 like CSS `large'. In troff output, the point size is increased
150 by 5; in MathML output, the expression uses
151 <mstyle mathsize='big'>
153 e1 smallover e2
155 This is similar to over; smallover reduces the size of e1 and
156 e2; it also puts less vertical space between e1 or e2 and the
157 fraction bar. The over primitive corresponds to the TeX \over
158 primitive in display styles; smallover corresponds to \over in
159 non-display styles.
160 vcenter e
162 This vertically centers e about the math axis. The math axis is
163 the vertical position about which characters such as `+' and `−'
164 are centered; also it is the vertical position used for the bar
165 of fractions. For example, sum is defined as
166 { type "operator" vcenter size +5 \(*S }
168 (Note that vcenter is silently ignored when generating MathML.)
170 e1 accent e2
172 This sets e2 as an accent over e1. e2 is assumed to be at the
173 correct height for a lowercase letter; e2 is moved down accord‐
174 ing to whether e1 is taller or shorter than a lowercase letter.
175 For example, hat is defined as
176 accent { "^" }
178 dotdot, dot, tilde, vec, and dyad are also defined using the
180 accent primitive.
181 e1 uaccent e2
183 This sets e2 as an accent under e1. e2 is assumed to be at the
184 correct height for a character without a descender; e2 is moved
185 down if e1 has a descender. utilde is pre-defined using uaccent
186 as a tilde accent below the baseline.
187 split "text"
189 This has the same effect as simply
190 text
192 but text is not subject to macro expansion because it is quoted;
194 text is split up and the spacing between individual characters
195 is adjusted.
196 nosplit text
198 This has the same effect as
199 "text"
201 but because text is not quoted it is subject to macro expansion;
203 text is not split up and the spacing between individual charac‐
204 ters is not adjusted.
205 e opprime
207 This is a variant of prime that acts as an operator on e. It
208 produces a different result from prime in a case such as
209 A opprime sub 1: with opprime the 1 is tucked under the prime as
210 a subscript to the A (as is conventional in mathematical type‐
211 setting), whereas with prime the 1 is a subscript to the prime
212 character. The precedence of opprime is the same as that of bar
213 and under, which is higher than that of everything except accent
214 and uaccent. In unquoted text a ' that is not the first charac‐
215 ter is treated like opprime.
216 special text e
218 This constructs a new object from e using a troff(1) macro named
219 text. When the macro is called, the string 0s contains the out‐
220 put for e, and the number registers 0w, 0h, 0d, 0skern, and
221 0skew contain the width, height, depth, subscript kern, and skew
222 of e. (The subscript kern of an object says how much a sub‐
223 script on that object should be tucked in; the skew of an object
224 says how far to the right of the center of the object an accent
225 over the object should be placed.) The macro must modify 0s so
226 that it outputs the desired result with its origin at the cur‐
227 rent point, and increase the current horizontal position by the
228 width of the object. The number registers must also be modified
229 so that they correspond to the result.
230 For example, suppose you wanted a construct that `cancels' an
232 expression by drawing a diagonal line through it.
233 .EQ
235 define cancel 'special Ca'
236 .EN
237 .de Ca
238 . ds 0s \
239 \Z'\\*(0s'\
240 \v'\\n(0du'\
241 \D'l \\n(0wu -\\n(0hu-\\n(0du'\
242 \v'\\n(0hu'
243 ..
244 Then you could cancel an expression e with cancel { e }
246 Here's a more complicated construct that draws a box round an
248 expression:
249 .EQ
251 define box 'special Bx'
252 .EN
253 .de Bx
254 . ds 0s \
255 \Z'\h'1n'\\*(0s'\
256 \Z'\
257 \v'\\n(0du+1n'\
258 \D'l \\n(0wu+2n 0'\
259 \D'l 0 -\\n(0hu-\\n(0du-2n'\
260 \D'l -\\n(0wu-2n 0'\
261 \D'l 0 \\n(0hu+\\n(0du+2n'\
262 '\
263 \h'\\n(0wu+2n'
264 . nr 0w +2n
265 . nr 0d +1n
266 . nr 0h +1n
267 ..
268 space n
270 A positive value of the integer n (in hundredths of an em) sets
271 the vertical spacing before the equation, a negative value sets
272 the spacing after the equation, replacing the default values.
273 This primitive provides an interface to groff's \x escape (but
274 with opposite sign).
275 This keyword has no effect if the equation is part of a pic pic‐
277 ture.
278 Extended primitives
280 col n { ... }
281 ccol n { ... }
282 lcol n { ... }
283 rcol n { ... }
284 pile n { ... }
285 cpile n { ... }
286 lpile n { ... }
287 rpile n { ... }
288 The integer value n (in hundredths of an em) increases the ver‐
289 tical spacing between rows, using groff's \x escape (the value
290 has no effect in MathML mode). Negative values are possible but
291 have no effect. If there is more than a single value given in a
292 matrix, the biggest one is used.
293 Customization
295 When eqn is generating troff markup, the appearance of equations is
296 controlled by a large number of parameters. They have no effect when
297 generating MathML mode, which pushes typesetting and fine motions down‐
298 stream to a MathML rendering engine. These parameters can be set using
299 the set command.
300 set p n
302 This sets parameter p to value n; n is an integer. For example,
303 set x_height 45
305 says that eqn should assume an x height of 0.45 ems.
307 Possible parameters are as follows. Values are in units of hun‐
309 dredths of an em unless otherwise stated. These descriptions
310 are intended to be expository rather than definitive.
311 minimum_size
313 eqn doesn't set anything at a smaller point-size than
314 this. The value is in points.
315 fat_offset
317 The fat primitive emboldens an equation by overprinting
318 two copies of the equation horizontally offset by this
319 amount. This parameter is not used in MathML mode;
320 instead, fat text uses
321 <mstyle mathvariant='double-struck'>
323 over_hang
325 A fraction bar is longer by twice this amount than the
326 maximum of the widths of the numerator and denominator;
327 in other words, it overhangs the numerator and denomina‐
328 tor by at least this amount.
329 accent_width
331 When bar or under is applied to a single character, the
332 line is this long. Normally, bar or under produces a
333 line whose length is the width of the object to which it
334 applies; in the case of a single character, this tends to
335 produce a line that looks too long.
336 delimiter_factor
338 Extensible delimiters produced with the left and right
339 primitives have a combined height and depth of at least
340 this many thousandths of twice the maximum amount by
341 which the sub-equation that the delimiters enclose
342 extends away from the axis.
343 delimiter_shortfall
345 Extensible delimiters produced with the left and right
346 primitives have a combined height and depth not less than
347 the difference of twice the maximum amount by which the
348 sub-equation that the delimiters enclose extends away
349 from the axis and this amount.
350 null_delimiter_space
352 This much horizontal space is inserted on each side of a
353 fraction.
354 script_space
356 The width of subscripts and superscripts is increased by
357 this amount.
358 thin_space
360 This amount of space is automatically inserted after
361 punctuation characters.
362 medium_space
364 This amount of space is automatically inserted on either
365 side of binary operators.
366 thick_space
368 This amount of space is automatically inserted on either
369 side of relations.
370 x_height
372 The height of lowercase letters without ascenders such as
373 `x'.
374 axis_height
376 The height above the baseline of the center of characters
377 such as `+' and `−'. It is important that this value is
378 correct for the font you are using.
379 default_rule_thickness
381 This should set to the thickness of the \(ru character,
382 or the thickness of horizontal lines produced with the \D
383 escape sequence.
384 num1 The over command shifts up the numerator by at least this
386 amount.
387 num2 The smallover command shifts up the numerator by at least
389 this amount.
390 denom1 The over command shifts down the denominator by at least
392 this amount.
393 denom2 The smallover command shifts down the denominator by at
395 least this amount.
396 sup1 Normally superscripts are shifted up by at least this
398 amount.
399 sup2 Superscripts within superscripts or upper limits or
401 numerators of smallover fractions are shifted up by at
402 least this amount. This is usually less than sup1.
403 sup3 Superscripts within denominators or square roots or sub‐
405 scripts or lower limits are shifted up by at least this
406 amount. This is usually less than sup2.
407 sub1 Subscripts are normally shifted down by at least this
409 amount.
410 sub2 When there is both a subscript and a superscript, the
412 subscript is shifted down by at least this amount.
413 sup_drop
415 The baseline of a superscript is no more than this much
416 amount below the top of the object on which the super‐
417 script is set.
418 sub_drop
420 The baseline of a subscript is at least this much below
421 the bottom of the object on which the subscript is set.
422 big_op_spacing1
424 The baseline of an upper limit is at least this much
425 above the top of the object on which the limit is set.
426 big_op_spacing2
428 The baseline of a lower limit is at least this much below
429 the bottom of the object on which the limit is set.
430 big_op_spacing3
432 The bottom of an upper limit is at least this much above
433 the top of the object on which the limit is set.
434 big_op_spacing4
436 The top of a lower limit is at least this much below the
437 bottom of the object on which the limit is set.
438 big_op_spacing5
440 This much vertical space is added above and below limits.
441 baseline_sep
443 The baselines of the rows in a pile or matrix are nor‐
444 mally this far apart. In most cases this should be equal
445 to the sum of num1 and denom1.
446 shift_down
448 The midpoint between the top baseline and the bottom
449 baseline in a matrix or pile is shifted down by this much
450 from the axis. In most cases this should be equal to
451 axis_height.
452 column_sep
454 This much space is added between columns in a matrix.
455 matrix_side_sep
457 This much space is added at each side of a matrix.
458 draw_lines
460 If this is non-zero, lines are drawn using the \D escape
461 sequence, rather than with the \l escape sequence and the
462 \(ru character.
463 body_height
465 The amount by which the height of the equation exceeds
466 this is added as extra space before the line containing
467 the equation (using \x). The default value is 85.
468 body_depth
470 The amount by which the depth of the equation exceeds
471 this is added as extra space after the line containing
472 the equation (using \x). The default value is 35.
473 nroff If this is non-zero, then ndefine behaves like define and
475 tdefine is ignored, otherwise tdefine behaves like define
476 and ndefine is ignored. The default value is 0 (This is
477 typically changed to 1 by the eqnrc file for the ascii,
478 latin1, utf8, and cp1047 devices.)
479 A more precise description of the role of many of these parame‐
481 ters can be found in Appendix H of The TeXbook.
482 Macros
484 Macros can take arguments. In a macro body, $n where n is between 1
485 and 9, is replaced by the n-th argument if the macro is called with
486 arguments; if there are fewer than n arguments, it is replaced by noth‐
487 ing. A word containing a left parenthesis where the part of the word
488 before the left parenthesis has been defined using the define command
489 is recognized as a macro call with arguments; characters following the
490 left parenthesis up to a matching right parenthesis are treated as
491 comma-separated arguments; commas inside nested parentheses do not ter‐
492 minate an argument.
493 sdefine name X anything X
495 This is like the define command, but name is not recognized if
496 called with arguments.
497 include "file"
499 copy "file"
500 Include the contents of file (include and copy are synonyms).
501 Lines of file beginning with .EQ or .EN are ignored.
502 ifdef name X anything X
504 If name has been defined by define (or has been automatically
505 defined because name is the output device) process anything;
506 otherwise ignore anything. X can be any character not appearing
507 in anything.
508 undef name
510 Remove definition of name, making it undefined.
511 Besides the macros mentioned above, the following definitions are
513 available: Alpha, Beta, ..., Omega (this is the same as ALPHA, BETA,
514 ..., OMEGA), ldots (three dots on the base line), and dollar.
515 Fonts
517 eqn normally uses at least two fonts to set an equation: an italic font
518 for letters, and a roman font for everything else. The existing gfont
519 command changes the font that is used as the italic font. By default
520 this is I. The font that is used as the roman font can be changed
521 using the new grfont command.
522 grfont f
524 Set the roman font to f.
525 The italic primitive uses the current italic font set by gfont; the
527 roman primitive uses the current roman font set by grfont. There is
528 also a new gbfont command, which changes the font used by the bold
529 primitive. If you only use the roman, italic and bold primitives to
530 changes fonts within an equation, you can change all the fonts used by
531 your equations just by using gfont, grfont and gbfont commands.
532 You can control which characters are treated as letters (and therefore
534 set in italics) by using the chartype command described above. A type
535 of letter causes a character to be set in italic type. A type of digit
536 causes a character to be set in roman type.
537
539 /usr/share/groff/1.22.2/tmac/eqnrc
540 Initialization file.
541
543 MathML is designed on the assumption that it cannot know the exact
544 physical characteristics of the media and devices on which it will be
545 rendered. It does not support fine control of motions and sizes to the
546 same degree troff does. Thus:
547 * eqn parameters have no effect on the generated MathML.
549 * The special, up, down, fwd, and back operations cannot be imple‐
551 mented, and yield a MathML `<merror>' message instead.
552 * The vcenter keyword is silently ignored, as centering on the
554 math axis is the MathML default.
555 * Characters that eqn over troff sets extra large – notably the
557 integral sign – may appear too small and need to have their
558 `<mstyle>' wrappers adjusted by hand.
559 As in its troff mode, eqn in MathML mode leaves the .EQ and .EN delim‐
561 iters in place for displayed equations, but emits no explicit delim‐
562 iters around inline equations. They can, however, be recognized as
563 strings that begin with `<math>' and end with `</math>' and do not
564 cross line boundaries.
565 See the BUGS section for translation limits specific to eqn.
567
569 Inline equations are set at the point size that is current at the
570 beginning of the input line.
571 In MathML mode, the mark and lineup features don't work. These could,
573 in theory, be implemented with `<maligngroup>' elements.
574 In MathML mode, each digit of a numeric literal gets a separate `<mn>
576 </mn>' pair, and decimal points are tagged with `<mo></mo>'. This is
577 allowed by the specification, but inefficient.
578
580 groff(1), troff(1), pic(1), groff_font(5), The TeXbook
581Groff Version 1.22.2 7 February 2013 EQN(1)