rtsi.com/2014.01.www.rtsi.com.tar/www.rtsi.com/OS9/OSK/APPS/lout2.lzh/LOUT2/DOC/TR.BEGIN/s02

Text File | 1994-01-25 | 5KB | 134 lines

@Section
   @Tag { displays }
   @Title { Displays }
@Begin
@PP
The @Code "@Display" symbol displays the following thing in the centre
of the page or column:
@ID @Code "@Display @I Centred"
has result
@Display @I Centred
Notice that @Code "@I Centred" does not have to be grouped within braces;
it is already a single thing.  Spaces (@Code "@DP" symbols) are inserted
automatically above and below the display, so no paragraph symbols are
needed anywhere near the display.
@PP
The display can be made to appear at the left margin by using the
{@Code "@LeftDisplay"} symbol instead of {@Code "@Display"}, or indented
by using {@Code "@IndentedDisplay"}.  There are also @Code "@CentredDisplay"
and @Code "@CenteredDisplay" symbols which are the same as
{@Code "@Display"}.  In general, the word @Code Centred may be spelt
@Code Centered wherever it appears.
@PP
Each display symbol has a `raw' version, which means that no space is
inserted above or below; the user must therefore add paragraph symbols:
@ID @Code {
"... preceding text."
"@DP"
"@RawIndentedDisplay @I Emma"
"@DP"
"@RawIndentedDisplay @I"
"{ Mansfield Park }"
"@DP"
"following text ..."
}
has result
@ID {
... preceding text.
@DP
@RawIndentedDisplay @I Emma
@DP
@RawIndentedDisplay @I { Mansfield Park }
@DP
following text ...
}
The point of this particular example is that two consecutive non-raw
displays would be separated by two @Code "@DP" symbols, which is too
much.  A better way to do this, using a list, will be presented in the
next section.
@PP
Displays may be {@I aligned}, which means that nominated points within a
sequence of displays are made to appear directly beneath each
other.  Displays may also be {@I numbered}, which means that an
automatically generated number is placed at the right-hand margin.  For
example, here is a first display:
@BeginNumberedDisplays
@BeginAlignedDisplays
@CentredAlignedNumberedDisplay
  @Tag { fibeq }
@Eq { F sub n ^= F sub n-1 + F sub n-2 }
and here is a second display, which is aligned on its @Eq {equal} sign
with the first, and also numbered in sequence with it:
@CentredAlignedNumberedDisplay
@Eq { F sub n - F sub n-1 ^= F sub n-2 }
@EndNumberedDisplays
@EndAlignedDisplays
Mathematical examples have been chosen because they are the most common
aligned and numbered displays; but any kind of display may be aligned or
numbered.
@PP
Notice that the two displays are centred as a block as well as
aligned.  Altogether then we have four ways in which displays vary:
@BL
@LI { A display can be raw or not raw; }
@LI { It can be a {@Code "@Display"}, {@Code "@LeftDisplay"},
{@Code "@IndentedDisplay"}, {@Code "@CentredDisplay"} or
{@Code "@CenteredDisplay"}; }
@LI { It can be aligned or not aligned; }
@LI { It can be numbered or not numbered. }
@EL
All possible combinations are allowed.  The display that has everything
is called
@ID @Code { "@RawCentredAlignedNumberedDisplay" &0io }
By leaving out some or all of {@Code Raw}, {@Code Aligned}, and
{@Code Numbered}, and by changing or leaving out {@Code Centred},
we get all these combinations.
@PP
When aligned displays are used, it is necessary to indicate where the
aligned group begins and ends, by inserting @Code "@BeginAlignedDisplays"
just before the first, and @Code "@EndAlignedDisplays" just after the
last.  The alignment points are indicated by preceding them by the
symbol {@Code "^"}.  Numbered displays are similarly bracketed by
@Code "@BeginNumberedDisplays" and {@Code "@EndNumberedDisplays"}.  So
then, with the help of the @Code "@Eq" equation formatting package
[{@Ref kingston92eq}], here is the input for the two displays given
earlier:
@ID @Code {
"... a first display:"
"@BeginNumberedDisplays"
"@BeginAlignedDisplays"
"@CentredAlignedNumberedDisplay"
"  @Tag { fibeq }"
@OneCol { "@Eq { F sub n ^= F sub n-1 + F sub n-2 }" &0io }
"and ... in sequence with it:"
"@CentredAlignedNumberedDisplay"
@OneCol { "@Eq { F sub n - F sub n-1 ^= F sub n-2 }" &0io }
"@EndNumberedDisplays"
"@EndAlignedDisplays"
"Mathematical examples ..."
}
No braces need enclose @Code "@Eq { ... }" because it is already a
single entity.  The @Code "@Tag { fibeq }" part is optional and is
explained in Section {@NumberOf cross}.  Alignment and numbering work
quite independently; they don't have to start or end together, and there
can be non-aligned and non-numbered displays among the others.
@PP
@Code "@BeginNumberedDisplays" has two {@I options}:  subsidiary
symbols which modify the result.  For example,
@ID @Code {
"@BeginNumberedDisplays"
"   style { [tag] }"
"   start { 12.5 }"
}
will cause the associated numbered displays to be labelled [12.5],
[12.6], and so on.  The first label is the @Code style option with
@Code tag replaced by the @Code start option.  Font changes and other
symbols are acceptable within the @Code style option.  When omitted, the
options have default values @Code "(tag)" and @Code "1" respectively.
@PP
Every symbol introduced in this section has an abbreviated form
consisting of @Code "@" followed by its capital letters only.  For
example, @Code "@BeginNumberedDisplays" can be abbreviated to {@Code "@BND"},
and the display that has everything to {@Code "@RCAND"}.
@End @Section