1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
|
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<!-- This document is an unofficial reference manual for LaTeX, a
document preparation system, version of October 2018.
This manual was originally translated from LATEX.HLP v1.0a in the
VMS Help Library. The pre-translation version was written by
George D. Greenwade of Sam Houston State University. The
LaTeX 2.09 version was written by Stephen Gilmore. The
LaTeX2e version was adapted from this by Torsten Martinsen. Karl
Berry made further updates and additions, and gratefully acknowledges
using Hypertext Help with LaTeX, by Sheldon Green, and
LaTeX Command Summary (for LaTeX 2.09) by
L. Botway and C. Biemesderfer (published by the TeX Users
Group as TeXniques number 10), as reference material. We also
gratefully acknowledge additional material appearing in
latex2e-reference by Martin Herbert Dietze. (From these references no
text was directly copied.)
Copyright 2007, 2008, 2009, 2010, 2011, 2012, 2013,
2014, 2015, 2016, 2017, 2018 Karl Berry.
Copyright 1988, 1994, 2007 Stephen Gilmore.
Copyright 1994, 1995, 1996 Torsten Martinsen.
Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.
Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the entire
resulting derived work is distributed under the terms of a permission
notice identical to this one.
Permission is granted to copy and distribute translations of this manual
into another language, under the above conditions for modified versions. -->
<!-- Created by GNU Texinfo 6.5, http://www.gnu.org/software/texinfo/ -->
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Lengths (LaTeX2e unofficial reference manual (October 2018))</title>
<meta name="description" content="Lengths (LaTeX2e unofficial reference manual (October 2018))">
<meta name="keywords" content="Lengths (LaTeX2e unofficial reference manual (October 2018))">
<meta name="resource-type" content="document">
<meta name="distribution" content="global">
<meta name="Generator" content="makeinfo">
<link href="latex2e_0.html#Top" rel="start" title="Top">
<link href="latex2e_30.html#Index" rel="index" title="Index">
<link href="latex2e_0.html#SEC_Contents" rel="contents" title="Table of Contents">
<link href="latex2e_0.html#Top" rel="up" title="Top">
<link href="latex2e_15.html#Making-paragraphs" rel="next" title="Making paragraphs">
<link href="latex2e_13.html#g_t_005cday-_0026-_005cmonth-_0026-_005cyear" rel="prev" title="\day & \month & \year">
<style type="text/css">
<!--
body {margin: 1em; margin-top: 0px; padding-top: 1px}
a.anchor {float: right}
a.summary-letter {text-decoration: none}
blockquote.indentedblock {margin-right: 0em}
blockquote.smallindentedblock {margin-right: 0em; font-size: smaller}
blockquote.smallquotation {font-size: smaller}
div.display {margin-left: 3.2em}
div.example {margin-left: 3.2em}
div.lisp {margin-left: 3.2em}
div.smalldisplay {margin-left: 3.2em}
div.smallexample {margin-left: 3.2em}
div.smalllisp {margin-left: 3.2em}
kbd {font-style: oblique}
pre.display {font-family: inherit}
pre.format {font-family: inherit}
pre.menu-comment {font-family: serif}
pre.menu-preformatted {font-family: serif}
pre.smalldisplay {font-family: inherit; font-size: smaller}
pre.smallexample {font-size: smaller}
pre.smallformat {font-family: inherit; font-size: smaller}
pre.smalllisp {font-size: smaller}
span.nolinebreak {white-space: nowrap}
span.roman {font-family: initial; font-weight: normal}
span.sansserif {font-family: sans-serif; font-weight: normal}
ul.no-bullet {list-style: none}
-->
</style>
</head>
<body id="top" lang="en">
<a name="Lengths" class="anchor"></a>
<a name="Lengths-1" class="anchor"></a>
<h2 class="chapter">Lengths</h2>
<a name="index-lengths_002c-defining-and-using" class="anchor"></a>
<p>A <em>length</em> is a measure of distance. Many LaTeX commands take a
length as an argument.
</p>
<p>Lengths come in two types. A <em>rigid length</em> such as <code>10pt</code>
does not contain a <code>plus</code> or <code>minus</code> component. (Plain TeX
calls this a <em>dimen</em>.) A <em>rubber length</em> (what Plain TeX
calls a <em>skip</em>) such as as with <code>1cm plus0.05cm minus0.01cm</code>
can contain either or both of those components. In that rubber length,
the <code>1cm</code> is the <em>natural length</em> while the other two, the
<code>plus</code> and <code>minus</code> components, allow TeX to stretch or
shrink the length to optimize placement.
</p>
<p>The illustrations below use these two commands.
</p>
<div class="example">
<pre class="example">% make a black bar 10pt tall and #1 wide
\newcommand{\blackbar}[1]{\rule{#1}{10pt}}
% Make a box around #2 that is #1 wide (excluding the border)
\newcommand{\showhbox}[2]{%
\fboxsep=0pt\fbox{\hbox to #1{#2}}}
</pre></div>
<p>This example uses those commands to show a black bar 100 points
long between ‘<samp>XXX</samp>’ and ‘<samp>YYY</samp>’. This length is rigid.
</p>
<div class="example">
<pre class="example">XXX\showhbox{100pt}{\blackbar{100pt}}YYY
</pre></div>
<p>As for rubber lengths, shrinking is simpler one: with <code>1cm minus
0.05cm</code>, the natural length is 1cm but TeX can shrink it down
as far as 0.95cm. Beyond that, TeX refuses to shrink any more.
Thus, below the first one works fine, producing a space of
98 points between the two bars.
</p>
<div class="example">
<pre class="example">XXX\showhbox{300pt}{%
\blackbar{101pt}\hspace{100pt minus 2pt}\blackbar{101pt}}YYY
XXX\showhbox{300pt}{%
\blackbar{105pt}\hspace{100pt minus 1pt}\blackbar{105pt}}YYY
</pre></div>
<p>But the second one gets a warning like ‘<samp>Overfull \hbox (1.0pt too
wide) detected at line 17</samp>’. In the output the first ‘<samp>Y</samp>’ is
overwritten by the end of the black bar, because the box’s material is
wider than the 300pt allocated, as TeX has refused to shrink
the total to less than 309 points.
</p>
<p>Stretching is like shrinking except that if TeX is asked to stretch
beyond the given amount, it will do it. Here the first line is fine,
producing a space of 110 points between the bars.
</p>
<div class="example">
<pre class="example">XXX\showhbox{300pt}{%
\blackbar{95pt}\hspace{100pt plus 10pt}\blackbar{95pt}}YYY
XXX\showhbox{300pt}{%
\blackbar{95pt}\hspace{100pt plus 1pt}\blackbar{95pt}}YYY
</pre></div>
<p>In the second line TeX needs a stretch of 10 points and only
1 point was specified. TeX stretches the space to the required
length but it gives you a warning like ‘<samp>Underfull \hbox (badness
10000) detected at line 22</samp>’. (We won’t discuss badness.)
</p>
<p>You can put both stretch and shrink in the same length, as in
<code>1ex plus 0.05ex minus 0.02ex</code>.
</p>
<p>If TeX is setting two or more rubber lengths then it allocates the
stretch or shrink in proportion.
</p>
<div class="example">
<pre class="example">XXX\showhbox{300pt}{%
\blackbar{100pt}% left
\hspace{0pt plus 50pt}\blackbar{80pt}\hspace{0pt plus 10pt}% middle
\blackbar{100pt}}YYY % right
</pre></div>
<p>The left and right bars take up 100 points, so the middle needs
another 100. The middle bar is 80 points so the two
<code>\hspace</code>’s must stretch 20 points. Because the two are
<code>plus 50pt</code> and <code>plus 10pt</code>, TeX gets 5/6 of the stretch
from the first space and 1/6 from the second.
</p>
<p>The <code>plus</code> or <code>minus</code> component of a rubber length can contain
a <em>fill</em> component, as in <code>1in plus2fill</code>. This gives the
length infinite stretchability or shrinkability so that TeX could set
it to any distance. Here the two figures will be equal-spaced across
the page.
</p>
<div class="example">
<pre class="example">\begin{minipage}{\linewidth}
\hspace{0pt plus 1fill}\includegraphics{godel.png}%
\hspace{0pt plus 1fill}\includegraphics{einstein.png}%
\hspace{0pt plus 1fill}
\end{minipage}
</pre></div>
<p>TeX actually has three levels of infinity for glue components:
<code>fil</code>, <code>fill</code>, and <code>filll</code>. The later ones are more
infinite than the earlier ones. Ordinarily document authors only use
the middle one (see <a href="latex2e_19.html#g_t_005chfill">\hfill</a> and see <a href="latex2e_19.html#g_t_005cvfill">\vfill</a>).
</p>
<p>Multiplying a rubber length by a number turns it into a rigid length, so
that after <code>\setlength{\ylength}{1in plus 0.2in}</code> and
<code>\setlength{\zlength}{3\ylength}</code> then the value of
<code>\zlength</code> is <code>3in</code>.
</p>
<hr>
<a name="Units-of-length" class="anchor"></a>
<a name="Units-of-length-1" class="anchor"></a>
<h3 class="section">Units of length</h3>
<a name="index-units_002c-of-length" class="anchor"></a>
<p>TeX and LaTeX know about these units both inside and outside of
math mode.
</p>
<dl compact="compact">
<dt><code>pt</code></dt>
<dd><a name="index-pt" class="anchor"></a>
<a name="index-Point" class="anchor"></a>
<a name="units-of-length-pt" class="anchor"></a><p>Point, 1/72.27 inch. The conversion to metric units, to two decimal
places, is 1point = 2.85mm = 28.45cm.
</p>
</dd>
<dt><code>pc</code></dt>
<dd><a name="index-pica" class="anchor"></a>
<a name="index-pc" class="anchor"></a>
<a name="units-of-length-pc" class="anchor"></a><p>Pica, 12 pt
</p>
</dd>
<dt><code>in</code></dt>
<dd><a name="index-in" class="anchor"></a>
<a name="index-inch" class="anchor"></a>
<a name="units-of-length-in" class="anchor"></a><p>Inch, 72.27 pt
</p>
</dd>
<dt><code>bp</code></dt>
<dd><a name="index-bp" class="anchor"></a>
<a name="index-Big-point" class="anchor"></a>
<a name="units-of-length-bp" class="anchor"></a><p>Big point, 1/72 inch. This length is the definition of a point in
PostScript and many desktop publishing systems.
</p>
</dd>
<dt><code>cm</code></dt>
<dd><a name="index-Centimeter" class="anchor"></a>
<a name="index-cm" class="anchor"></a>
<a name="units-of-length-cm" class="anchor"></a><p>Centimeter
</p>
</dd>
<dt><code>mm</code></dt>
<dd><a name="index-Millimeter" class="anchor"></a>
<a name="index-mm" class="anchor"></a>
<a name="units-of-length-mm" class="anchor"></a><p>Millimeter
</p>
</dd>
<dt><code>dd</code></dt>
<dd><a name="index-Didot-point" class="anchor"></a>
<a name="index-dd" class="anchor"></a>
<a name="units-of-length-dd" class="anchor"></a><p>Didot point, 1.07 pt
</p>
</dd>
<dt><code>cc</code></dt>
<dd><a name="index-Cicero" class="anchor"></a>
<a name="index-cc" class="anchor"></a>
<a name="units-of-length-cc" class="anchor"></a><p>Cicero, 12 dd
</p>
</dd>
<dt><code>sp</code></dt>
<dd><a name="index-Scaled-point" class="anchor"></a>
<a name="index-sp" class="anchor"></a>
<a name="units-of-length-sp" class="anchor"></a><p>Scaled point, 1/65536 pt
</p>
</dd>
</dl>
<a name="index-ex" class="anchor"></a>
<a name="index-x_002dheight" class="anchor"></a>
<a name="index-ex-1" class="anchor"></a>
<a name="index-m_002dwidth" class="anchor"></a>
<a name="index-em" class="anchor"></a>
<a name="index-em-1" class="anchor"></a>
<a name="Lengths_002fem" class="anchor"></a><a name="Lengths_002fen" class="anchor"></a><a name="Lengths_002fex" class="anchor"></a><a name="units-of-length-em" class="anchor"></a><a name="units-of-length-en" class="anchor"></a><a name="units-of-length-ex" class="anchor"></a><p>Two other lengths that are often used are values set by the designer of
the font. The x-height of the current font <em>ex</em>, traditionally the
height of the lowercase letter x, is often used for vertical
lengths. Similarly <em>em</em>, traditionally the width of the capital
letter M, is often used for horizontal lengths (there is also
<code>\enspace</code>, which is <code>0.5em</code>). Use of these can help make a
definition work better across font changes. For example, a definition
of the vertical space between list items given as
<code>\setlength{\itemsep}{1ex plus 0.05ex minus 0.01ex}</code> is more
likely to still be reasonable if the font is changed than a definition
given in points.
</p>
<a name="index-mu_002c-math-unit" class="anchor"></a>
<a name="index-mu" class="anchor"></a>
<p>In math mode, many definitions are expressed in terms of the math unit
<em>mu</em> given by 1 em = 18 mu, where the em is taken from the current
math symbols family. See <a href="latex2e_16.html#Spacing-in-math-mode">Spacing in math mode</a>.
</p>
<hr>
<a name="g_t_005csetlength" class="anchor"></a>
<a name="g_t_005csetlength-1" class="anchor"></a>
<h3 class="section"><code>\setlength</code></h3>
<a name="index-_005csetlength" class="anchor"></a>
<a name="index-lengths_002c-setting" class="anchor"></a>
<p>Synopsis:
</p>
<div class="example">
<pre class="example">\setlength{<var>len</var>}{<var>amount</var>}
</pre></div>
<p>Set the length <var>len</var> to <var>amount</var>. The length name <var>len</var>
must begin with a backslash, <code>\</code>. The <code>amount</code> can be a
rubber length (see <a href="#Lengths">Lengths</a>). It can be positive, negative or zero,
and can be in any units that LaTeX understands (see <a href="#Units-of-length">Units of length</a>).
</p>
<p>Below, with LaTeX’s defaults the first paragraph will be indented
while the second will not.
</p>
<div class="example">
<pre class="example">I told the doctor I broke my leg in two places.
\setlength{\parindent}{0em}
He said stop going to those places.
</pre></div>
<p>If you did not declare <var>len</var> with <code>\newlength</code>, for example if
you mistype the above as
<code>\newlength{\specparindent}\setlength{\sepcparindent}{...}</code>,
then you get an error like ‘<samp>Undefined control sequence. <argument>
\sepcindent</samp>’. If you omit the backslash at the start of the length name
then you get an error like ‘<samp>Missing number, treated as zero. <to be
read again> \relax l.19 \setlength{specparindent}{0.6\parindent}</samp>’
</p>
<hr>
<a name="g_t_005caddtolength" class="anchor"></a>
<a name="g_t_005caddtolength-1" class="anchor"></a>
<h3 class="section"><code>\addtolength</code></h3>
<a name="index-_005caddtolength" class="anchor"></a>
<a name="index-lengths_002c-adding-to" class="anchor"></a>
<p>Synopsis:
</p>
<div class="example">
<pre class="example">\addtolength{<var>len</var>}{<var>amount</var>}
</pre></div>
<p>Increment the length <var>len</var> by <var>amount</var>. The length name
<var>len</var> begins with a backslash, <code>\</code>. The <code>amount</code> is a
rubber length (see <a href="#Lengths">Lengths</a>). It can be positive, negative or zero,
and can be in any units that LaTeX understands (see <a href="#Units-of-length">Units of length</a>).
</p>
<p>Below, if <code>\parskip</code> starts with the value <code>0pt plus 1pt</code>
</p>
<div class="example">
<pre class="example">Doctor: how is the boy who swallowed the silver dollar?
\addtolength{\parskip}{1pt}
Nurse: no change.
</pre></div>
<p>then it has the value <code>1pt plus 1pt</code> for the second paragraph.
</p>
<p>If you did not declare the length <var>len</var> with <code>\newlength</code>, if
for example you mistype the above as
<code>\addtolength{\specparindent}{0.6\praindent}</code>, then you get
something like ‘<samp>Undefined control sequence. <argument> \praindent</samp>’.
If you leave off the backslash at the start of <var>len</var>, as in
<code>\addtolength{parindent}{1pt}</code>, then you get something like
‘<samp>You can't use `the letter p' after \advance</samp>’.
</p>
<hr>
<a name="g_t_005csettodepth" class="anchor"></a>
<a name="g_t_005csettodepth-1" class="anchor"></a>
<h3 class="section"><code>\settodepth</code></h3>
<a name="index-_005csettodepth" class="anchor"></a>
<p>Synopsis:
</p>
<div class="example">
<pre class="example">\settodepth{<var>len</var>}{<var>text</var>}
</pre></div>
<p>Set the length <var>len</var> to the depth of box that LaTeX gets on
typesetting the <var>text</var> argument. The length name <var>len</var> must
begin with a backslash, <code>\</code>.
</p>
<p>This will show how low the character descenders go.
</p>
<div class="example">
<pre class="example">\newlength{\alphabetdepth}
\settodepth{\alphabetdepth}{abcdefghijklmnopqrstuvwxyz}
\the\alphabetdepth
</pre></div>
<p>If you did not set aside the length <var>len</var>, if for example you
mistype the above as <code>\settodepth{\aplhabetdepth}{abc...}</code>,
then you get something like ‘<samp>Undefined control sequence. <argument>
\aplhabetdepth</samp>’. If you leave the backslash out of <var>len</var>, as in
<code>\settodepth{alphabetdepth}{...}</code> then you get something like
‘<samp>Missing number, treated as zero. <to be read again> \setbox</samp>’.
</p>
<hr>
<a name="g_t_005csettoheight" class="anchor"></a>
<a name="g_t_005csettoheight-1" class="anchor"></a>
<h3 class="section"><code>\settoheight</code></h3>
<a name="index-_005csettoheight" class="anchor"></a>
<p>Synopsis:
</p>
<div class="example">
<pre class="example">\settoheight{<var>len</var>}{text}
</pre></div>
<p>Sets the length <var>len</var> to the height of box that LaTeX gets on
typesetting the <code>text</code> argument. The length name <var>len</var> must
begin with a backslash, <code>\</code>.
</p>
<p>This will show how high the characters go.
</p>
<div class="example">
<pre class="example">\newlength{\alphabetheight}
\settoheight{\alphabetheight}{abcdefghijklmnopqrstuvwxyz}
\the\alphabetheight
</pre></div>
<p>If no such length <var>len</var> has been declared with <code>\newlength</code>, if
for example you mistype as
<code>\settoheight{\aplhabetheight}{abc...}</code>, then you get something
like ‘<samp>Undefined control sequence. <argument> \alphabetheight</samp>’. If
you leave the backslash out of <var>len</var>, as in
<code>\settoheight{alphabetheight}{...}</code> then you get something like
‘<samp>Missing number, treated as zero. <to be read again> \setbox</samp>’.
</p>
<hr>
<a name="g_t_005csettowidth" class="anchor"></a>
<a name="g_t_005csettowidth-1" class="anchor"></a>
<h3 class="section"><code>\settowidth</code></h3>
<a name="index-_005csettowidth" class="anchor"></a>
<p>Synopsis:
</p>
<div class="example">
<pre class="example">\settowidth{<var>len</var>}{<var>text</var>}
</pre></div>
<p>Set the length <var>len</var> to the width of the box that LaTeX gets on
typesetting the <var>text</var> argument. The length name <var>len</var> must
begin with a backslash, <code>\</code>.
</p>
<p>This measures the width of the lowercase ASCII alphabet.
</p>
<div class="example">
<pre class="example">\newlength{\alphabetwidth}
\settowidth{\alphabetwidth}{abcdefghijklmnopqrstuvwxyz}
\the\alphabetwidth
</pre></div>
<p>If no such length <var>len</var> has been set aside, if for example you
mistype the above as <code>\settowidth{\aplhabetwidth}{abc...}</code>,
then you get something like ‘<samp>Undefined control sequence. <argument>
\aplhabetwidth</samp>’. If you leave the backslash out of <var>len</var>, as in
<code>\settoheight{alphabetwidth}{...}</code> then you get something like
‘<samp>Missing number, treated as zero. <to be read again> \setbox</samp>’.
</p>
</body>
</html>
|
