4. Blocks

4.1. Function

A block is a separate part of the text that must be treated in a specific way. Blocks can be a separate consttruct or an inline version. for a separate construct, add a blank line above and below the block definition. For an in-line, keep the block within the current construct.

The following block-types exist:

Most block types will accept a format line

.block format <format>

with <format>:

A combination like halfright or leftquart is possible as long as they are sensical.

4.2. Pre-formatted block

A pre-formatted block is made with the .pre requests. A pre-formatted block should never be in-line but always a separate construct. As an example:

 .pre
  aaaaa
   aa
  aaaaa
 .pre

gives:

 aaaaa
  aa
 aaaaa

A preformatted text that is longer (for example a listing) or a text that doesn't need the enclosing box can be handled as .lst block.

 .lst #include <stdio.h>
 .lst int main() {
 .lst    printf("Hello, World!");
 .lst    return 0;
 .lst }

gives:

4.3. Pic

Pic is a language for drawing simple pictures. The pic block allows the use of these pictures.

 .block pic
 circle
 arrow
 box
 arrow
 circle "with text"
 .block

gives:

Example pic-block

Contrary to groff's use of pic, pic blocks can also be used in-line like this.

4.4. Eqn

Like pic, eqn allows embedding equations in the text.

 .block eqn
 pi r sup 2
 .block

gives

Example eqn-block

Eqn blocks can also be used in-line. For simple, in-line equations, the request .eqn is available. So,

 .eqn pi r sup 3

gives as result.

4.5. Gnuplot

Gnuplot can be used to draw plots. Only the plot needs to be specified. In3 will automatically set display, papersize et cetera. As an example:

 .block gnuplot
 $mydata <<EOD
 1 0-10  8   2.67
 2 10-15 14  4.67
 3 15-20 43  14.33
 4 20-25 106 35.33
 5 25-30 166 55.33
 6 30-35 240 80
 7 35-40 269 89.67
 8 40-45 283 94.33
 9 45-50 298 99.33
 10 >50  300 100.00
 EOD
 set yrange [0:110]
 set title "Speed cumulative"
 set arrow from 1,50 to 4.74,50 nohead
 set arrow from 4.74,0 to 4.74,50 nohead
 plot $mydata using 1:4:xtic(2) w lp notitle
 .block

For the use of gnuplot blocks it is required that gnuplot is installed on the system.

4.6. Music

Like gnuplot, Lilypond can be used to create music staffs.

 .block music
 \relative c'' {
 \new PianoStaff <<
 \new Staff { \time 2/4 c4 e | g g, | }
 \new Staff { \clef "bass" c,,4 c' | e c | }
 >>
 }
 .block

produces:

Again, all the paper, display etc. options will be set by In3.

4.7. Texeqn

Some people dislike the eqn-formatting and/or need more complex equations. For those cases, the texeqn block can be used. Normally, Tex requires a lot of document definitions before anything can be written. In3 takes care of all that. So

 .block texeqn
 \begin{align*}
 S(\omega)
 &= \frac{\alpha g^2}{\omega^5} e^{[ -0.74\bigl\{\frac{\omega U_\omega 19.5}{g}\bigr\}^{\!-4}\,]} \\
 &= \frac{\alpha g^2}{\omega^5} \exp\Bigl[ -0.74\Bigl\{\frac{\omega U_\omega 19.5}{g}\Bigr\}^{\!-4}\,\Bigr]
 \end{align*}
 .block

becomes:

4.8. Piechart

With the distribution you might get a copy of Sam Hocevar's piechart program. Because it has a DWTFYW-license I incorporated it in the ditribution of in3xml. The tables must have the order value, explode, color and legend. So, for example, if the data is:

The block would be:

 .block piechart
 25,10,red,not ok
 25,20,yellow,warn
 25,30,blue,unknown
 150,0,green,ok
 .block

with the result:

Note that the format for the block is a combined format here: left for having the piechart on the left and quart for the size.