21 KiB
Pandoc Markdown
Much documentation is in Pandoc markdown, because easier to write. But html is easier to read, and allows superior control of appearance
To convert Pandoc markdown to its final html form, invoke Pandoc by the bash
shell file ./mkdoc.sh, which generates html.
In the windows 10 environment, shell scripts used in this project need to be associated with Git Bash or run from within Git Bash.
If the title in the markdown file is followed by # katex, as in
the markdown form of this file, the shell script will tell Pandoc to display
any formulae using katex in the html file.
More precisely, if any of the first three lines in the yaml header specifying
the title at the start of the markdown file are # katex, the ./mkdoc.sh
will tell Pandoc to use katex to display maths formula.
This vast pile of notes is out of control, and writing code and maths in html leads to intolerable overheads.
Hence markdown, the popular markdown conversion program being the open source Pandoc.
Markdown converters are apt to throw a flood of incomprehensible html code into your final document, taking low level html control away from the writer.
Pandoc, however, will allow you to take control. To integrate html and css with markdown using Pandoc is a bit like rolling marbles with your elbows through a cage. One has to work through and around the entry points that Pandoc gives you, while if you were writing in html you could just write what you damn well wanted directly, but having done the work, Pandoc can then ensure it is done for every document in the same style in the same way, and you can change the final form of every document in the same way all at once.
Sphinx is very popular and widely used, and written in the far more accessible language python, but to access the power of html, css, and JavaScript one must write a Sphinx theme, and the creation of a Sphinx theme is less than well documented and appears to be subject to change.
Visual Studio Code theoretically does automatic generation of the html equivalents of markdown files, but I never was able to get it working satisfactorily.
Pandoc has a number of powerful extensions that allow integration of html and
markdown, among them markdown native mode divs :::
::: {style="…"}
…
:::
And native mode spans […]{style="…"}
Which extensions do not work correctly in Visual Studio Code.
These can be used to put an anchor in text, but the easiest and most intelligible way to insert an anchor is as a header.
Pandoc can do a good job of rendering math markdown without invoking katex, and in such cases, one should generate the html
fn=filename
pandoc --toc --eol=lf --wrap=preserve --from markdown+ascii_identifiers --to html --metadata=lang:en --verbose --include-in-header=./pandoc_templates/header.pandoc --include-before-body=./pandoc_templates/before.pandoc --include-after-body=./pandoc_templates/after.Pandoc -o $fn.html $fn.md
Since markdown has no concept of a title, Pandoc expects to find the title in a yaml inline, which is most conveniently put at the top, which renders it somewhat legible as a title.
Thus the markdown version of this document starts with:
---
title: >-
Writing and Editing Documentation
# katex
---
Converting html source to markdown source
In bash
fn=foobar
git mv $fn.html $fn.md && cp $fn.md $fn.html && pandoc -s --to markdown-smart --eol=lf --wrap=preserve --verbose -o $fn.md $fn.html
Math expressions and katex
Pandoc can render most maths markdown without needing katex, for example:
{e}^{i\pi}+1=0a=b+cf(x) = x^2\sin(\pi/6) = 0.5\int_a^b f(x) dx\int_a^b \tan(x) dx\int \sin(x) dx = \cos(x)\sum a_i\lfloor{(x+5)÷6}\rfloor = \lceil{(x÷6}\rceil\lfloor{(x+5)/6}\rfloor = \lceil{(x/6}\rceilUsing Omicron, \bigcirc, not capital O for big \bigcirc. \Omicron will not always
compile correctly, but \ln and \log is more likely to compile correctly than
ln and log, which it tends to render as symbols multiplied, rather than one
symbol.
\ln(1+x)=x-\bigcirc(x^2)H(a|b|v)though it is subtly prettier with katex, and some maths expressions will break Pandoc unless one tells it to use katex.
Some maths, Pandoc needs katex:
\sin(\frac{\pi}{6}) = \frac12\displaystyle\frac{u(x)}{v(x)}Inline equation \displaystyle\sum\limits_{i=1}^n i^2 = \frac{n(n+1)(2n+1)}{6} text after inline equation
\displaystyle\sum\limits_{i} i^2 = \frac{i(i+1)(2i+1)}6The square root of 100 is \sqrt{100}=10.
The cubic root of 64 is \sqrt[3]{64}=4
\bigg\lfloor\frac{x+5)}{6}\bigg\rfloor = \bigg\lceil{\frac{x}{6}}\bigg\rceilSo for documents requiring some heavy maths display, we convert from markdown
to html with, in the bash script ./mkdoc.sh:
fn=filename
pandoc --katex=./ --toc --eol=lf --wrap=preserve --from markdown --to html --metadata=lang:en --verbose --include-in-header=./pandoc_templates/header.pandoc --include-before-body=./pandoc_templates/before.pandoc --include-after-body=./pandoc_templates/after.pandoc -o $fn.html $fn.md
The ./ tells pandoc to expect to find the files
./katex.min.css
./katex.min.js
That a file needs katex is flagged for ./mkdoc.sh in the yaml header.
A file that does not need katex has the header:
---
title: >-
Document title
---
But if it does need katex, it has the header
---
title: >-
Document title
# katex
---
So that the bash script file ./mkdoc.sh will tell Pandoc to find the katex scripts.
For it offends me to put unnecessary fat in html files.
overly clever katex tricks
k \approx \frac{m\,l\!n(2)}{n}%uses\, to increase spacing, uses \! to merge letters, uses % for comments k \approx\frac{m\>\ln(2)}{n}%uses\> for a marginally larger increase in spacing and uses \ln, the escape for the well known function ln \exp\bigg(\frac{a+bt}{x}\bigg)=\huge e^{\bigg(\frac{a+bt}{x}\bigg)}%use the escape for well known functions, use text size setsk\text{, the number of hashes} \approx \frac{m\ln(2)}{n}% \text{} for render as text\def\mydef#1{\frac{#1}{1+#1}} \mydef{\mydef{\mydef{\mydef{y}}}}%katex macro diagrams
The best way to do diagrams is Inkscape and the Visual Studio Code scalable vector graphics extensions.
I decided to place the data directly inline in markdown because interfacing
scalable vector graphics files (svg files) to html can get complicated, and
interfacing the resulting complicated html to markdown can get more
complicated.
Inkscape files are unreadable, and once they are cleaned up, Inkscape cannot read them. To (irreversibly) clean up an Inkscape file, minify it in Visual Studio Code to get rid of all confusing mystery cruft inserted by Inkscape, edit it back into markdown compatible form, and reinsert it in the markdown file.
A sequence of straight lines is M point, L point, L point.
Z and z draw a straight line back to the beginning, use in conjunction with
fill="#red" , for example fill="#FF0000". If the line is open, fill="none"
Drawing smooth curves by typing in text is painful and slow, but so is drawing them in Inkscape. Inkscape is apt to do a series of C beziers with sharp corners between them, and when I try to fix the sharp corners, the bezier goes weird.
What Inkscape should do is let you manipulate a sequence of control points, and draw an M C S S ..S bezier to the point halfway between the final even numbered control point and the preceding control point, creating an additional control point by mirroring if the user only provides an odd number of control points.
What it does instead is complicated and mysterious.
To convert a sequence of straight lines into a smooth curve, you encounter
much grief matching the end of one bezier to the start of the next.
And if you do not match them, you get corners between beziers.
-
find the midpoint of each edge, or the midpoint of every second edge
When I say midpoint, somewhere along the line, close to where you want the turn to sharp, and far from where you want the turn to be gentle. -
A smooth curve starts a midpoint of first edge then:
C first vertex, second vertex, next midpoint S second next vertex next midpoint S second next vertex, next midpoint ... S second next vertex next midpoint ...
When I say second next vertex, I mean you skip a vertex, and thus do not have to find the preceding midpoint. But the implied vertex is the mirror of the preceding vertex, which if your midpoint is off, is not where you expect it to be.
If it fails to go through the midpoint parallel to what you think the endpoints are, you need to tinker the control point to reduce the discrepancy, or else it is apt to be off at subsequent midpoints. -
Or starts at midpoint of first edge then:
Q vertex midpoint T midpoint T midpoint ....
But the Q T T T chain is apt to act weird unless your midpoints are near the middle, because the implied vertex is the mirror of the preceding vertex, which may not be the vertex that you intended if your midpoint is not near the centre of the line segment to that vertex.
Using S and T has the enormous advantage that if your midpoint is a bit off to one side of the line segment or the other, you still get a smooth curve, no kinks between beziers But if it is too far off from the centre, your curve will be off from the line segments, often in weird, surprising, and complicated ways.
On the other hand, if you have a C or a Q bezier following a previous C or Q bezier, getting the join smooth is a bitch.
To find the midpoint of a line segment, I use M approximate midpoint
v6 v-12 v6 h6 h-12 h6 to mark the location with a cross.
To draw a long twisty curve, mark your intended path with a sequence of line segments, with your final line segment passing through your destination, because destination will be the midpoint of that line segment. Then do a M first point, C second point, third point, midpoint, then S even numbered vertex, midpoint following the even numbered vertex, starting with the fourth vertex and the midpoint to the fifth vertex. The midpoint of the final vertex will be your destination.
Scalable vector graphics are dimensionless, and the <svg> tag's height,
width, and ViewBox properties translate the dimensionless quantities into
pixels. The graphics default to fixed aspect ratio, and anything outside
the viewbox is not drawn. To adjust your image's position within the
viewbox, you put everything into a single big group, and apply a translate
to that group.
You need to set an Inkscape tools properties from an existing element that you have manually edited as text, as a great deal of functionality is only available by editing vector graphics as text, and attempting to manipulate that functionality from Inkscape, though in theory possible, just creates an uncontrollable mess.
Every so often, a tool's properties get set to something stupid for some stupid reason, and there is no fix available in the Inkscape UI, other than selecting a graphic element, double clicking on the tool, and telling it to take its defaults from the element selected. (which can be an entire group, or the entire high top level group, in which case it will pick up sane and appropriate properties from the first relevant item in the group.)
The enormous advantage of scalable vector graphics is that it handles repetitious items in diagrams beautifully, because you can define an item by reference to another item, thus very large hierarchical structure can be defined by very small source code.
You might decide to keep it around as soup, in an svg file that only
Inkscape ever tries to read, but then you are going to have to edit it as text
again. And I wound up embedding my vector graphics files in markdown
rather than invoking them as separate graphics files because my last step
was apt to be editing them as text. Which irreversibly made them
uneditable by Inkscape
It is convenient to construct and position all the graphical elements in
Inkscape, then edit the resulting svg file in Visual Studio Code with the
svg extension, watching the resulting graphic in the svg editor's preview
pane, then use the svg extension's minify command to get rid of all the
excess stuff generated by Inkscape, then edit the svg file to be compatible
with Markdown, then edit it into the markdown file, then edit the
markdown file in the Visual Studio Code markdown editor, watching the
graphic in the markdown preview pane.
<svg
xmlns="http://www.w3.org/2000/svg"
width="29em" height="12em"
viewBox="40 60 60 50"
style="background-color:ivory">
<g id="startblocks"
font-family="'Times New Roman'" font-size="5"
font-weight="400"
stroke-width="2"
style="text-decoration:underline; cursor:pointer;" >
<line x1="22" y1="70" x2="28" y2="100" stroke="lightgrey"/>
<rect style="fill:#FFFF00;"
x="12" y="64" width="36" height="20">
<animate attributeType="XML" attributeName="y"
from="64" to="120"
dur="5s" repeatCount="2" restart="always" />
</rect>
<text style="fill:blue;" x="14" y="74">
<animate attributeType="XML" attributeName="y"
from="74" to="130"
dur="5s" repeatCount="2" restart="always" />
start animation
</text>
</g>
<rect x="60" y="64" width="20" height="20">
<animate attributeType="XML" attributeName="y"
from="64" to="120"
dur="5s" repeatCount="3" restart="whenNotActive"/>
</rect>
<g
font-family="'Times New Roman'" font-size="5"
font-weight="400"
stroke-width="2">
<path fill="none" stroke="#00f000"
d="M14.629 101.381c25.856-20.072 50.69-56.814
54.433-18.37 3.742 38.443 40.484 15.309 40.484 15.309"/>
<ellipse cx="60" cy="85" rx="12" ry="5" style="fill:red" />
<text x="60" y="82" text-anchor="middle" style="fill:#A050C0;" >
A simple scalable vector graphic
<tspan x="60" dy="8">
directly embedded in markdown.
</tspan>
</text>
</g>
</svg>
<script>
document.getElementById("startblocks").addEventListener
(
"click", evt =>
{
document.querySelectorAll("animate").forEach
(
element =>
{
element.beginElement();
}
);
}
);
</script>
# tables
<table border="1" cellpadding="6" cellspacing="0" width="95%">
<tbody>
<tr>
<td colspan="2" style="background-color: #99CC66;
text-align:center;">May Scale of monetary hardness </td>
</tr>
<tr>
<td style="text-align:center;"><b> Hardness</b> </td>
<td> <br/>
</td>
</tr>
<tr>
<td colspan="2" style=" text-align:center;">Hard</td>
</tr>
<tr>
<td class="center"><b>1</b></td>
<td>Street cash, US dollars</td>
</tr>
<tr>
<td class="center"><b>2</b></td>
<td>Street cash, euro currencies, japan</td>
</tr>
<tr>
<td class="center"><b>3</b></td>
<td>Major crypto currencies, such as Bitcoin and Monaro</td>
</tr>
<tr>
<td class="center"><b>4</b></td>
<td>Street cash, other regions</td>
</tr>
<tr>
<td class="center"><b>5</b></td>
<td>Interbank transfers of various sorts (wires etc),
bank checks</td>
</tr>
<tr>
<td class="center"><b>6</b></td>
<td>personal checks</td>
</tr>
<tr>
<td class="center"><b>7</b>
</td>
<td>Consumer-level electronic account transfers (eg
bPay)</td>
</tr>
<tr>
<td class="center"><b>8</b></td>
<td>Business-account-level retail transfer systems</td>
</tr>
<tr>
<td colspan="2" style=" text-align:center;">Soft</td>
</tr>
<tr>
<td class="center"><b>9</b></td>
<td>Paypal and similar 'new money' entities, beenz</td>
</tr>
<tr>
<td class="center"><b>10</b></td>
<td>Credit cards</td>
</tr>
</tbody>
</table>
Tables
Pipe table with header and alignment control
Without counting spaces, but without multiline
Pipe table:
| Right | Left | Default | Center |
|---|---|---|---|
| 12 | 12 | 12 | 12 |
| 123 | 123 | 123 | the quick brown fox jumped over the lazy dog |
| 1 | 1 | Carrian Corporation | 1 |
And, with less mucking about, alignments
with alignment, without counting spaces, but without multiline
| fruit | price |
|---|---|
| apple | 2.05 |
| pear | 1.37 |
| orange | 3.09 |
multiline without bothering with pipes
Counting spaces to align. Only editable in fixed font
This allows multiline, but visual studio code does not like it. Visual Studio Code only supports tables that can be intelligibly laid out in visual studio code.
Centered Default Right Left Header Aligned Aligned Aligned
First row 12.0 Example of a row that spans multiple lines.
Second row 5.0 Here's another one. Note the blank line between rows.
The header may be omitted in multiline tables as well as simple tables
Notice the alignment is controlled by the first item in a column
In this table, edited in a fixed font, you are using whitespace and blank lines to lay out the table. It is unintellible in a variable width font.
First row 12.0 Example of a row that spans multiple lines.
Second row 5.0 Here's another one. Note the blank line between rows.
Grid tables
Allows multiline, and alignment, but visual studio does not like it, and you still have to count those spacees
+---------------+---------------+--------------------+ | Fruit | Price | Advantages | +===============+==============:+====================+ | Bananas | $1.34 | - built-in wrapper | | | | - bright color | +---------------+---------------+--------------------+ | Oranges | $2.10 | - cures scurvy | | | | - tasty | +---------------+---------------+--------------------+ | Durian | $22.10 | - king of fruits | +---------------+---------------+--------------------+
Alignments can be specified as with pipe tables, by putting colons at the boundaries of the separator line after the header.
+------------+---------+---------------------+ | Left | Right | Centered | +:===========+========:+:===================:+ | Bananas | $1.34 | - built-in wrapper | | | | - bright color | +------------+---------+---------------------+ | Durian | $22.10 | - king of fruits | +------------+---------+---------------------+
For headerless tables, the colons go on the top line instead:
+--------------:+:--------------+:------------------:+ | Right | Left | Centered | +---------------+---------------+--------------------+