Christopher Choi chutsu

Chroot Jail - Ubuntu 20.04 + ROS Noetic

sudo bash bootstrap.bash     # creates a chroot jail at $HOME/bootstrap
sudo chroot $HOME/bootstrap  # Type exit to exit the chroot jail

Configure Apple Magic Keyboard in Ubuntu

In-order to:

Enable function keys by default
Swap option (alt) with command key
Swap fn with left-ctrl key

on the Apple Magic Keyboard:

Kensington Expert Mouse Button Mapping

Back               Forward
      [Track ball]
Left-click         Right-click

xinput set-button-map "Kensington Expert Wireless TB Mouse" 1 8 3 4 5 6 7 9

The following code snippet showcases how one would use Eigen's spline module to fit x^2 and find the first and second derivatives along the spline.

An important note is to remember to scale the derivatives with:

(x - x_min) / (x_max - x_min) (first derivative)
(x - x_min) / (x_max - x_min)^2 (second derivative).

Because when fitting a spline to x^2, the x values you feed into the spline fitter is actually normalized with (x - x_min) / (x_max - x_min). So using

Eigen has an unsupported spline module where you can fit a spline given some data. Once a spline is fitted you can use it as a function to obtain points inbetween. The following example fits 1D data but can be modified to fit N-dimensional data.

Usage

 git clone https://gist.github.com/chutsu/815c7c916c329eec85f34690a012f7cb spline_example
 g++ -I/usr/include/eigen3 spline_example.cpp -o spline_example

./spline_example

	/**
	* Solving Ax = b using Cholesky Decomposition in C using LAPACK
	* Compile with: gcc test_chol.c -lblas -llapack -llapacke -o test_chol
	*/
	#include <stdio.h>
	#include <lapacke.h>

	int main() {
	// Define matrix A and vector b in A * x = b
	// clang-format off