November 2019 Updates

  • Added information on masked arrays to the Numpy page.

  • Added Euler Angle support (e.g. RPY) to the 3D rotations calculator.

  • New introduction to different map projections.

  • Added a new React page.

October 2019 Updates

  • 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).

A screenshot of the 3D rotation visualizer and converter.

A screenshot of the 3D rotation visualizer and converter.

September 2019 Updates

August 2019 Updates

  • New tutorial on Standard Deviations.

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

July 2019 Updates

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