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Copyright (C) 1989-2000, 2001 Free Software Foundation, Inc.
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Permission is granted to make and distribute verbatim copies of
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this manual provided the copyright notice and this permission notice
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are preserved on all copies.
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Permission is granted to copy and distribute modified versions of this
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manual under the conditions for verbatim copying, provided that the
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entire resulting derived work is distributed under the terms of a
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permission notice identical to this one.
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Permission is granted to copy and distribute translations of this
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manual into another language, under the above conditions for modified
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versions, except that this permission notice may be included in
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translations approved by the Free Software Foundation instead of in
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.ie \n(.V<\n(.v .ds tx T\h'-.1667m'\v'.224m'E\v'-.224m'\h'-.125m'X
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.\" Like TP, but if specified indent is more than half
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.\" the current line-length - indent, use the default indent.
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.ie \\n(.$=0:((0\\$1)*2u>(\\n(.lu-\\n(.iu)) .TP
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.\" The BSD man macros can't handle " in arguments to font change macros,
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.\" so use \(ts instead of ".
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.TH @G@EQN @MAN1EXT@ "@MDATE@" "Groff Version @VERSION@"
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@g@eqn \- format equations for troff
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.ie \\n(.$-1 .RI "[\ \fB\\$1\fP" "\\$2" "\ ]"
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.el .RB "[\ " "\\$1" "\ ]"
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.RI "[\ " files\|.\|.\|. "\ ]"
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It is possible to have whitespace between a command line option and its
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This manual page describes the GNU version of
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which is part of the groff document formatting system.
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compiles descriptions of equations embedded within
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input files into commands that are understood by
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Normally, it should be invoked using the
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The syntax is quite compatible with Unix eqn.
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The output of GNU eqn cannot be processed with Unix troff;
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it must be processed with GNU troff.
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If no files are given on the command line, the standard input
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will cause the standard input to be read.
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in the directories given with the
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.BR @SYSTEMMACRODIR@ ,
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and finally in the standard macro directory
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If it exists, eqn will process it before the other input files.
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GNU eqn does not provide the functionality of neqn:
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it does not support low-resolution, typewriter-like devices
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(although it may work adequately for very simple input).
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even when followed by a character other than space or newline.
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Don't allow newlines within delimiters.
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to recover better from missing closing delimiters.
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Print the version number.
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Only one size reduction.
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The minimum point-size is
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eqn will not reduce the size of subscripts or superscripts to
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The output is for device
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The only effect of this is to define a macro
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will use this to provide definitions appropriate for the output device.
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The default output device is
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before the default directories.
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This is equivalent to a
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This is equivalent to a
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This option is deprecated.
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eqn will normally set equations at whatever the current point size
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is when the equation is encountered.
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This says that subscripts and superscripts should be
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points smaller than the surrounding text.
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This option is deprecated.
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Normally eqn makes sets subscripts and superscripts at 70%
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of the size of the surrounding text.
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Only the differences between GNU eqn and Unix eqn are described here.
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Most of the new features of GNU eqn
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There are some references to the differences between \*(tx and GNU eqn below;
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these may safely be ignored if you do not know \*(tx.
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.SS Automatic spacing
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gives each component of an equation a type, and adjusts the spacing
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between components using that type.
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.TP \w'punctuation'u+2n
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an ordinary character such as 1 or
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a large operator such as
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.if \n(.g .if !c\(*S .ds Su the summation operator
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a binary operator such as +;
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a relation such as =;
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a opening bracket such as (;
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a closing bracket such as );
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a punctuation character such as ,;
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a subformula contained within brackets;
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spacing that suppresses automatic spacing adjustment.
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Components of an equation get a type in one of two ways.
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This yields an equation component that contains
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is one of the types mentioned above.
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The name of the type doesn't have to be quoted, but quoting protects
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from macro expansion.
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.BI chartype\ t\ text
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Unquoted groups of characters are split up into individual characters,
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and the type of each character is looked up;
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this changes the type that is stored for each character;
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it says that the characters in
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from now on have type
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chartype "punctuation" .,;:
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would make the characters
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have type punctuation
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whenever they subsequently appeared in an equation.
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changes the font type of the characters.
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See the Fonts subsection.
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.IB e1\ smallover\ e2
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it also puts less vertical space between
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and the fraction bar.
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primitive corresponds to the \*(tx
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primitive in display styles;
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in non-display styles.
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This vertically centers
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The math axis is the vertical position about which characters
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such as + and - are centered; also it is the vertical position
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used for the bar of fractions.
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{ type "operator" vcenter size +5 \e(*S }
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is assumed to be at the correct height for a lowercase letter;
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will be moved down according if
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is taller or shorter than a lowercase letter.
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are also defined using the
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is assumed to be at the correct height for a character without a descender;
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will be moved down if
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as a tilde accent below the baseline.
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.BI split\ \(ts text \(ts
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This has the same effect as simply
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is not subject to macro expansion because it is quoted;
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will be split up and the spacing between individual characters
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This has the same effect as
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is not quoted it will be subject to macro expansion;
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and the spacing between individual characters will not be adjusted.
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that acts as an operator on
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It produces a different result from
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.BR A\ opprime\ sub\ 1 :
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will be tucked under the prime as a subscript to the
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(as is conventional in mathematical typesetting),
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will be a subscript to the prime character.
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is the same as that of
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which is higher than that of everything except
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that is not the first character will be treated like
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This constructs a new object from
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.BR @g@troff (@MAN1EXT@)
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When the macro is called,
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will contain the output for
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and the number registers
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will contain the width, height, depth, subscript kern, and skew of
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of an object says how much a subscript on that object should be tucked in;
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of an object says how far to the right of the center of the object an
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accent over the object should be placed.)
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The macro must modify
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so that it will output the desired result with its origin at the current
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point, and increase the current horizontal position by the width
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The number registers must also be modified so that they correspond to the
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For example, suppose you wanted a construct that `cancels' an expression
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by drawing a diagonal line through it.
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define cancel 'special Ca'
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\&.ds 0s \eZ'\e\e*(0s'\ev'\e\en(0du'\eD'l \e\en(0wu -\e\en(0hu-\e\en(0du'\ev'\e\en(0hu'
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Then you could cancel an expression
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Here's a more complicated construct that draws a box round an expression:
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define box 'special Bx'
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\&.ds 0s \eZ'\eh'1n'\e\e*(0s'\e
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\eZ'\ev'\e\en(0du+1n'\eD'l \e\en(0wu+2n 0'\eD'l 0 -\e\en(0hu-\e\en(0du-2n'\e
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\eD'l -\e\en(0wu-2n 0'\eD'l 0 \e\en(0hu+\e\en(0du+2n''\eh'\e\en(0wu+2n'
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The appearance of equations is controlled by
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a large number of parameters. These can be set using
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should assume an x height of 0.45 ems.
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Possible parameters are as follows.
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Values are in units of hundredths of an em unless otherwise stated.
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These descriptions are intended to be expository rather than
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.TP \w'\fBdefault_rule_thickness'u+2n
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will not set anything at a smaller point-size than this.
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The value is in points.
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primitive emboldens an equation
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by overprinting two copies of the equation
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horizontally offset by this amount.
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A fraction bar will be longer by twice this amount than
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the maximum of the widths of the numerator and denominator;
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in other words, it will overhang the numerator and
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denominator by at least this amount.
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is applied to a single character,
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the line will be this long.
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produces a line whose length is the width of the object to which it applies;
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in the case of a single character,
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this tends to produce a line that looks too long.
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Extensible delimiters produced with the
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primitives will have a combined height and depth of at least this many
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thousandths of twice the maximum amount by which the sub-equation that
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the delimiters enclose extends away from the axis.
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.B delimiter_shortfall
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Extensible delimiters produced with the
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primitives will have a combined height and depth
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not less than the difference of
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twice the maximum amount by which the sub-equation that
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the delimiters enclose extends away from the axis
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.B null_delimiter_space
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This much horizontal space is inserted
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on each side of a fraction.
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The width of subscripts and superscripts is increased by this amount.
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This amount of space is automatically inserted after punctuation
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This amount of space is automatically inserted on either side
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This amount of space is automatically inserted on either side of
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The height of lowercase letters without ascenders such as x.
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The height above the baseline of the center of characters
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such as \(pl and \(mi.
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It is important that this value is correct for the font
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.B default_rule_thickness
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This should set to the thickness of the
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character, or the thickness of horizontal lines produced with the
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command will shift up the numerator by at least this amount.
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command will shift up the numerator by at least this amount.
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command will shift down the denominator by at least this amount.
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command will shift down the denominator by at least this amount.
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Normally superscripts will be shifted up by at least this amount.
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Superscripts within superscripts or upper limits
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will be shifted up by at least this amount.
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This is usually less than sup1.
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Superscripts within denominators or square roots
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or subscripts or lower limits will be shifted up by at least
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This is usually less than sup2.
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Subscripts will normally be shifted down by at least this amount.
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When there is both a subscript and a superscript, the subscript
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will be shifted down by at least this amount.
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The baseline of a superscript will be no more
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than this much amount below the top of the object on
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which the superscript is set.
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The baseline of a subscript will be at least this much below
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the bottom of the object on which the subscript is set.
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The baseline of an upper limit will be at least this
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much above the top of the object on which the limit is set.
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The baseline of a lower limit will be at least this
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much below the bottom of the object on which the limit is set.
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The bottom of an upper limit will be at least this much above the
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top of the object on which the limit is set.
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The top of a lower limit will be at least this much below
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the bottom of the object on which the limit is set.
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This much vertical space will be added above and below limits.
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The baselines of the rows in a pile or matrix will normally be
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In most cases this should be equal to the sum of
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The midpoint between the top baseline and the bottom baseline
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in a matrix or pile will be shifted down by this much from the axis.
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In most cases this should be equal to
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This much space will be added between columns in a matrix.
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This much space will be added at each side of a matrix.
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If this is non-zero, lines will be drawn using the
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escape sequence, rather than with the
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escape sequence and the
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The amount by which the height of the equation exceeds this
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will be added as extra space before the line containing the equation
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The default value is 85.
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The amount by which the depth of the equation exceeds this
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will be added as extra space after the line containing the equation
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The default value is 35.
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The default value is 0
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(This is typically changed to 1 by the
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A more precise description of the role of many of these
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parameters can be found in Appendix H of
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Macros can take arguments.
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will be replaced by the
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argument if the macro is called with arguments;
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if there are fewer than
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arguments, it will be replaced by nothing.
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A word containing a left parenthesis where the part of the word
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before the left parenthesis has been defined using the
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will be recognized as a macro call with arguments;
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characters following the left parenthesis
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up to a matching right parenthesis will be treated as comma-separated
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commas inside nested parentheses do not terminate an argument.
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.BI sdefine\ name\ X\ anything\ X
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will not be recognized if called with arguments.
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.BI include\ \(ts file \(ts
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Include the contents of
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.BI ifdef\ name\ X\ anything\ X
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(or has been automatically defined because
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is the output device)
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can be any character not appearing in
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normally uses at least two fonts to set an equation:
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an italic font for letters,
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and a roman font for everything else.
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changes the font that is used as the italic font.
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The font that is used as the roman font can be changed
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Set the roman font to
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primitive uses the current italic font set by
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primitive uses the current roman font set by
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command, which changes the font used by the
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primitives to changes fonts within an equation,
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you can change all the fonts used by your equations
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You can control which characters are treated as letters
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(and therefore set in italics) by using the
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command described above.
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will cause a character to be set in italic type.
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will cause a character to be set in roman type.
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.Tp \w'\fB@MACRODIR@/eqnrc'u+2n
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Inline equations will be set at the point size that is current at the
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beginning of the input line.
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.BR groff (@MAN1EXT@),
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.BR @g@troff (@MAN1EXT@),
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.BR groff_font (@MAN5EXT@),
added
removed
src/preproc/eqn/eqn.man
