Viewing posts by christian

The double compound pendulum

Following on from this post about the simple double pendulum, (two bobs connected by light, rigid rods), this post animates the double compound pendulum (also called a double complex or physical pendulum): two rods connected to each other, with their mass distributed along their length. The analysis on Wikipedia provides the dynamical equations for the case of equal-mass and equal-length rods. Here, the more general case of rods with lengths $l_1$ and $l_2$ and masses $m_1$ and $m_2$ is considered.

COVID-19 Quarantine House: Hollywood Walk of Fame Edition

To find your Hollywood Walk of Fame Quarantine house, use this script on the command line, providing your latitude and longitude:

Illustrating the Padovan sequence

The Padovan sequence is a cousin of the more famous Fibonacci sequence defined by the initial values $P(1)=P(2)=P(3)=1$ and the recurrence relation $P(n) = P(n-2) + P(n-3)$. That is, the next value is obtained not by summing the previous two values but by summing the two values before the last one. The first few values are:

Plotting COVID-19 case growth charts

Following on from this previous post, here is a short tutorial on creating this and similar charts using pandas by automatically downloading data from Johns Hopkins University's CSSE GitHub repository (the "JHU/CSSE dataset").

Plotting COVID-19 cases

The Centre for Systems Science and Engineering (CSSE) at Johns Hopkins University publishes daily statistics of the number of confirmed cases of COVID-19 by country on its GitHub page. The short script below pulls data from this page to plot a bar chart of cases and growth in cases as a function of time for a given country. For example: