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---
title: >-
Writing and Editing Documentation
# katex
---
# 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 ](libraries/git_bash_undocumented.html ) 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 `:::`
```markdown
::: {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
```bash
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:
```markdown
---
title: >-
Writing and Editing Documentation
# katex
---
```
# Converting html source to markdown source
In bash
```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:
$${e}^{i\pi}+1=0$$
$$a=b+c$$
$$f(x) = x^2$$
$$\sin(\pi/6) = 0.5$$
$$\int_a^b f(x) dx$$
$$\int_a^b \tan(x) dx$$
$$\int \sin(x) dx = \cos(x)$$
$$\sum a_i$$
$$\lfloor{(x+5)÷6}\rfloor = \lceil{(x÷6}\rceil$$
$$\lfloor{(x+5)/6}\rfloor = \lceil{(x/6}\rceil$$
Using 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
$$\displaystyle\sum\limits_{i} i^2 = \frac{i(i+1)(2i+1)}6$$
The square root of 100 is $\sqrt{100}=10$.\
The cubic root of 64 is $\sqrt[3]{64}=4$
$$\bigg\lfloor\frac{x+5)}{6}\bigg\rfloor = \bigg\lceil{\frac{x}{6}}\bigg\rceil$$
So for documents requiring some heavy maths display, we convert from markdown
to html with, in the bash script `./mkdoc.sh` :
```bash
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
```bash
./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:
```markdown
---
title: >-
Document title
---
```
But if it does need katex, it has the header
```markdown
---
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
$$k \approx \frac{m\,l\!n(2)}{n}%uses\, to increase spacing, uses \! to merge letters, uses % for comments $$
$$k \approx\frac{m\>\ln(2)}{n}%uses\> for a marginally larger increase in spacing and uses \ln, the escape for the well known function ln $$
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$$ \exp\bigg(\frac{a+bt}{x}\bigg)=\huge e^{\bigg(\frac{a+bt}{x}\bigg)}%use the escape for well known functions, use text size sets$$
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$$k\text{, the number of hashes} \approx \frac{m\ln(2)}{n}% \text{} for render as text$$
$$\def\mydef#1{\frac{#1}{1+#1}} \mydef{\mydef{\mydef{\mydef{y}}}}%katex macro $$
# 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.
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Inkscape files are unreadable, and once they are cleaned up, Inkscape
cannot read them. To (irreversibly) clean up an Inkscape file, minify it in
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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.
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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.
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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
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was apt to be editing them as text. Which irreversibly made them
uneditable by Inkscape
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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="110"
dur="5s" repeatCount="2" restart="always" />
< / rect >
< text style = "fill:blue;" x = "14" y = "74" >
< animate attributeType = "XML" attributeName = "y"
from="74" to="120"
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="3s" repeatCount="5" restart="whenNotActive"/>
< animate attributeType = "XML" attributeName = "x"
from="60" to="0"
dur="3s" repeatCount="5" restart="whenNotActive"/>< / rect >
< g
font-family="'Times New Roman'" font-size="5"
font-weight="400"
stroke-width="2">
< path fill = "none" stroke = "#00f000"
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d="M14 101, c40 -20, 30 -56,
54 -18, s60 15, 40 15"/>
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< 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 >
```svg
< 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
< 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 >
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```
# 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
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## multiline without bothering with pipes
Counting spaces to align. Only editable in fixed font
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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.
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-------------------------------------------------------------
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.
----------- ------- --------------- -------------------------
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## Grid tables
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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 |
+---------------+---------------+--------------------+
