Updated the mv (move) page with information on using extended bash glob extensions to provide exclusion patterns.

$ mkdir new_sub_dir # Create a new sub-directory to move all files/directories in PWD into
$ mv !(new_sub_dir) new_sub_dir # Move all files/directories in PWD into new_sub_dir, excluding new_sub_dir itself (avoiding the obvious recursion problem)

The Introduction To Rotation Matrices page has been updated with tutorials/example on how to combine rotation matrices and how to calculate the rotation matrix to describe the rotation between two reference frames, as well as a section on how to convert RPY (roll-pitch-yaw, or Euler angles) to rotation matrices.

$$ \mathbf{R} = \begin{bmatrix} \hat{u_x} & \hat{v_x} & \hat{w_x} \\ \hat{u_y} & \hat{v_y} & \hat{w_y} \\ \hat{u_z} & \hat{v_z} & \hat{w_z} \end{bmatrix} $$

Added an interactive 3D rotation visualizer to the Quaternion page, which shows you how a right-hand coordinate system XYZ is rotated in 3D space by either a rotation matrix, quaternion, or angle-axis rotation. This tool is also very useful to convert between the three ways of describing a rotation (when you enter a rotation in one notation, the other two get updated automatically).

The du (disk usage) page now has information on the -x flag which is used count the space used on one filesystem only.

New Introduction To Asynchronous Programming In Python with information on asynchronous programming in Python, including the keywords async/await, event loops, futures, coroutines and more.

Add a new Introduction To S3 page.

New tutorial on Standard Deviations.

Updated the Qt page with a section on how to allow file names with capital letters in Qt Creator.

New tutorial on the Modality Independent Neighbourhood Descriptor (MIND).

New tutorial on the Self-Similarity Context (SSC). This is related to MIND.

New section on Optimization.

New Satellites section under Space.

New tutorial on Jupyter (incl. Jupyter Notebooks and Jupyter Labs).

Updated the rm (remove) page with workaround examples for when you get the argument list too long error.

The page on Electronic Noise moved from Electronics->Test And Measurement to Electronics->Circuit Design.

Renamed the Fast Fourier Transform page to the Fourier Transform page, as it now contains information about other Fourier transforms.

Added graphs of 1D Fourier transformations:

and animated .gifs of 2D Fourier transformations:

Updated the pytest page with info on mark (markers) and pytest naming conventions.

Removed the updates directory that all monthly update posts were under.

Added a tutorial on pandas, a popular data analytics library for Python.

Updated the Python Debugging page with more info on pdb.

Updated the Passive Filters page with more information on low-pass RC filters, including plots of the frequency response:

I created a public mbedded.ninja project on CircuitMaker at https://workspace.circuitmaker.com/Projects/Details/GeoffreyHunter/mbedded-ninja. I am going to trial out CircuitMaker as a tool for drawing schematic diagrams for this blog. In the past I have used Altium (not free), MultisimLive and InkScape (free but is a general vector graphics editor, not a dedicated electronics CAD program).

Added the Command-Line CSV Viewer page, which contains information on how to cleanly view CSV files from the Linux command-line.

Added a new page about the programming language Julia.