Engineering Statics

Subsection C.3.1 MBX

MBX is the old name for the utility script. Now called pretext/pretext.

I had some trouble getting the mbx program working, with the message

  File "/Users/whaynes/ptx/mathbook/script/mbx", line 771, in youtube_thumbnail
    import requests
ImportError: No module named requests

I tried installing the requests module with

==>  sudo pip install requests

But it didn't work :(

The problem was that when I tried to import the requests module with pip, it got installed into the wrong version of python. I had to do this to straighten it out. I'm using macPorts.

==>  port select --list python
Available versions for python:
none
python27 (active)
python27-apple
python37 

 ==>  port select --list pip
Available versions for pip:
none
pip27
pip37 (active)

 ==>  sudo port select --set pip pip27
Selecting 'pip27' for 'pip' succeeded. 'pip27' is now active.

 ==>  sudo pip install requests

Also, to get the mbx program to work, I had to install pageres-cli which required installation of nodejs. On mac, this resulted in an installation error due to file permissions, and was resolved by installing pagres-cli this way sudo

> npm install --global pageres-cli --unsafe-perm=true

PDF Crop Margins 7/12/20

pdfcrop was deprecated here.

1. pip install pdfCropMargins
2. add python to path in .zshrc as noted by installation notes
3. kernel panic ???

whaynes:statics/ (master✗) $ pip install pdfCropMargins                                                                                              [11:55:10]
Defaulting to user installation because normal site-packages is not writeable
Collecting pdfCropMargins
  Downloading pdfCropMargins-0.2.8.tar.gz (1.8 MB)
     |████████████████████████████████| 1.8 MB 2.4 MB/s 
Collecting wheel
  Downloading wheel-0.34.2-py2.py3-none-any.whl (26 kB)
Collecting pillow>=6.2.2
  Downloading Pillow-7.2.0-cp37-cp37m-macosx_10_10_x86_64.whl (2.2 MB)
     |████████████████████████████████| 2.2 MB 15.3 MB/s 
Collecting PyPDF2
  Downloading PyPDF2-1.26.0.tar.gz (77 kB)
     |████████████████████████████████| 77 kB 5.0 MB/s 
Using legacy setup.py install for pdfCropMargins, since package 'wheel' is not installed.
Using legacy setup.py install for PyPDF2, since package 'wheel' is not installed.
Installing collected packages: wheel, pillow, PyPDF2, pdfCropMargins
  WARNING: The script wheel is installed in '/Users/whaynes/Library/Python/3.7/bin' which is not on PATH.
  Consider adding this directory to PATH or, if you prefer to suppress this warning, use --no-warn-script-location.
    Running setup.py install for PyPDF2 ... done
    Running setup.py install for pdfCropMargins ... done
Successfully installed PyPDF2-1.26.0 pdfCropMargins-0.2.8 pillow-7.2.0 wheel-0.34.2
whaynes:statics/ (master✗) $                                                                                                                         [11:59:27]

Subsection C.3.2 Geogebra Tips

Subsection C.3.3 Images

The preferred image types for the book for diagrams or drawings is Scalable Vector Graphics. This format should be used for any diagrams or drawings you make if possible. SVG files can be created with Inkscape, Geogebra, or other tools and can easily and accurately be converted to pdf documents. For photographs use Portable Network Graphics images (extension .png) if possible in preference to JPEG files. Any diagram you create should have an 'actual' height of about 100 mm or 4 inches, or taller if necessary, but not more that 1 page tall. Diagrams will get scaled down when they go into the book. On the web version, clicking on the scaled image will pop up a larger image.

You will need to create or obtain a image file and store it with the PreTeXt source.

Store all image files in the resources directory, in your chapter folder, and then in a folder named for the image. It's a good idea to include a text file in this directory with the copyright and source info for crediting the image. See Best Practices for Attribution. All ggb, jpg, png, svg, pdf and pdf_tex files will be copied from here to a common images folder for inclusion into the document. This way, images can be inserted by using their filename only. Since all images will be in the same folder, no path is necessary, but all filenames must be unique so avoid common names like fbd.svg.

There are several ways to include the images into the book.

Good. If you want to place an image with no caption, and no number, then you must wrap an <image> tag with a <sidebyside> tag, as so:

<sidebyside> <image source='filename.ext' width=75%' /></sidebyside>

You will also need to save the actual image file in the resources directory, from where it will be copied to the output. See the Pretext Docs for info on the sidebyside options.

If you want the image to have a caption and a number, wrap the <image> tag with a <figure> tag instead and give it a <title>.

Better. Include a svg image for html and an identical pdf diagram for LaTeX.

This produces better quality than method 1, because both svg and pdf files are vector based and therefore will scale properly if the document shrinks or grows. In this case you will need to create both files. Inkscape will read either, and export the other, so it is not difficult to produce both. Save both files in the resources directory. Note there is no extension included in the source attribute. PreTeXt will include the proper image for html in the html file and for LaTeX in the latex file.

In this case the command to include the image is the same as before, but leave off the three letter extension. PreTeXt will select svg for html and pdf for LaTeX.

<image source='filename' width=75%' />

PreTeXt/LaTeX can overlay text on top of a static image, so that the font matches the body text, and LaTeX formulas can be used in the diagram.

To do this you will need to create or edit an image using Inkscape or some other tool. In any event, open the svg file with Inkscape, and edit any text as necessary. LaTeX can be included in your labels, and colors and bold, and italic will be maintained but the text will use the document font. For annotated photographs, create a svg file and import the the png image, then use the SVG tools to add text and arrows, etc. Geogebra can export 2D files as svg. My CAD program doesn't natively export SVG files, but I can "print as pdf" and convert that file to an editable svg file using the command line tool pdf2svg.

When you are finished editing the svg file with Inkscape, save it as a svg file and also "save as pdf". Choose the option "omit text in pdf and create LaTeX file." and save this in the same directory. Alongside your svg image, two other files will be created, a pdf file with no text, and a pdf_tex file which is a standalone LaTeX file which overlays properly rendered text on top of the pdf image.

The incantation to include this file is

<image>
<latex-image>
\pdftex[12pt]{filename}
</latex-image>
</image>

The font side argument [12pt] is optional, but can be used to adjust the default size if necessary.

In Affinity designer, use 72 dpi and built-in fonts and latexit font sizes will agree:

Use Times to match body font

Use CMU fonts to match latex

When unscaled, 16 point font matches body font. as in first diagram. Here the original size was 300px by 300 px, and it was inserted at 50% width which is also 300 px. Lesson: if you know how wide the diagram will be in the book, draw it at that size and use 16 point fonts to match body text.

In second diagram the 300 px wide original is inserted at 100% which is 600 px, so doubled. Now every font is too big. Need to use a 8 pt font to double to 16 pt, I think.

Subsection C.3.4 Exercise for Examples

Announcement

<exercise>

• <p>

<exercise>

• <statement>
  • <p>
• <hint>
• <answer>
• <solution>

<exercise>

• <introduction>
• <task>
  • <statement>
  • <hint>
  • <answer>
  • <solution>
• <task>
• <task>
• <conclusion>

<exercise>

• <introduction>
• <task>
  • <introduction>
• <task>
  • <statement>
  • <hint>
  • <answer>
  • <solution>
  • <conclusion>
• <task>
• <task>
  • <conclusion>
• <conclusion>

investigation

prelude?

statement

Hint?

answer?

solution*

postlude

investigation

prelude?

introduction?

task+

conclusion?

postlude?

task

statement

hint?

answer?

solution?

task

introduction?

task+

solution?

task unstructured

Subsection C.3.5 Issues or questions for the developers

Issues with pretext

1. Can't put bare image in, need to wrap with sidebyside.?
2. Maybe use intro conclusion of task.
3. Can't have an intro and a statement in investigations.
4. How do I make a qed?
5. I want bold for double emphasis or highlight <alert>?.
6. Need better support of multi-step solutions
7. I'd like a procedure element.
8. maybe allow tasks in <solutions> for the steps
9. task needs title
10. allow paragraphs elements in <solutions> for lightweight divisions
11. Cant have a discussion within the task about multiple solutions
12. Steps need to permit hints
13. Would like to change the numbering of tasks/subtasks. Start with numbers, then letters, no bold. Would like a bold run in title though
14. Schema doesn't permit <paragraphs> in solution, but it seems to render.
15. Can I have an inline list? a. one, b. two, c. three
16. Intertext between mrows? I think so
17. <li> permits <title> Didn't know that. Couldn't find it in the documentation
18. <kbd> is in documentation but not in schema, I think
19. How can I change the chunking for <exercises> I'd like one numbas problem per page.