What's all this, then?
open-menu closeme
Home
Tags
About
  • Voting power

    calendar Dec 30, 2020 · 6 min read · voting  ·
    Share on: twitter facebook linkedin copy

    After the 2020 American Presidential election, with the usual post-election analyses and (in this case) vast numbers of lawsuits, I started looking at the Electoral College, and trying to work out how it worked in terms of power. Although power is often conflated simply with the number of votes, that’s not necessarily …


    Read More
  • Electing a president

    calendar Nov 7, 2020 · 6 min read · voting linear-programming julia  ·
    Share on: twitter facebook linkedin copy

    Every four years (barring death or some other catastrophe), the USA goes through the periodic madness of a presidential election. Wild behaviour, inaccuracies, mud-slinging from both sides have been central since George Washington’s second term. And the entire business of voting is muddied by the Electoral College, the …


    Read More
  • Enumerating the rationals

    calendar Jan 18, 2020 · 5 min read · mathematics  ·
    Share on: twitter facebook linkedin copy

    The rational numbers are well known to be countable, and one standard method of counting them is to put the positive rationals into an infinite matrix \(M=m_{ij}\), where \(m_{ij}=i/j\) so that you end up with something that looks like this: [ \left[\begin{array}{ccccc} …


    Read More
  • Fitting the SIR model of disease to data in Julia

    calendar Jan 15, 2020 · 3 min read · mathematics julia  ·
    Share on: twitter facebook linkedin copy

    A few posts ago I showed how to do this in Python. Now it’s Julia’s turn. The data is the same: spread of influenza in a British boarding school with a population of 762. This was reported in the British Medical Journal on March 4, 1978, and you can read the original short article here. As before we use the SIR model, …


    Read More
  • The Butera-Pernici algorithm (2)

    calendar Jan 6, 2020 · 6 min read · mathematics computation  ·
    Share on: twitter facebook linkedin copy

    The purpose of this post will be to see if we can implement the algorithm in Julia, and thus leverage Julia’s very fast execution time. We are working with polynomials defined on nilpotent variables, which means that the degree of any generator in a polynomial term will be 0 or 1. Assume that our generators are indexed …


    Read More
  • The Butera-Pernici algorithm (1)

    calendar Jan 4, 2020 · 4 min read · mathematics computation  ·
    Share on: twitter facebook linkedin copy

    Introduction We know that there is no general sub-exponential algorithm for computing the permanent of a square matrix. But we may very reasonably ask – might there be a faster, possibly even polynomial-time algorithm, for some specific classes of matrices? For example, a sparse matrix will have most terms of the …


    Read More
  • The size of the universe

    calendar Jan 2, 2020 · 7 min read · science astronomy  ·
    Share on: twitter facebook linkedin copy

    As a first blog post for 2020, I’m dusting off one from my previous blog, which I’ve edited only slightly. I’ve been looking up at the sky at night recently, and thinking about the sizes of things. Now it’s all very well to say something is for example a million kilometres away; that’s just a number, and as far as the …


    Read More
  • Permanents and Ryser’s algorithm :mathematics:computation:julia

    calendar Dec 22, 2019 · 9 min read  ·
    Share on: twitter facebook linkedin copy

    As I discussed in my last blog post, the permanent of an \(n\times n\) matrix \(M=m_{ij}\) is defined as

    \[ \text{per}(M)=\sum_{\sigma\in S_n}\prod_{i=1}^nm_{i,\sigma(i)} \]

    where the sum is taken over all permutations of the \(n\) numbers \(1,2,\ldots,n\). It differs from the better known determinant in having no sign …


    Read More
  • Speeds of Julia and Python

    calendar Dec 19, 2019 · 6 min read · programming python julia  ·
    Share on: twitter facebook linkedin copy

    Introduction Python is of course one of the world’s currently most popular languages, and there are plenty of statistics to show it. Of all languages in current use, Python is one of the oldest (in the very quick time-scale of programming languages) dating from 1990 - only C and its variants are older. However, it …


    Read More
  • Poles of inaccessibility

    calendar Dec 8, 2019 · 4 min read · image-processing julia  ·
    Share on: twitter facebook linkedin copy

    Just recently there was a news item about a solo explorer being the first Australian to reach the Antarctic “Pole of Inaccessibility”. Such a Pole is usually defined as that place on a continent that is furthest from the sea. The South Pole is about 1300km from the nearest open sea, and can be reached by specially …


    Read More
    • ««
    • «
    • 3
    • 4
    • 5
    • 6
    • 7
    • »
    • »»

Recent Posts

  • Self-avoiding walks: other grids
  • Self-avoiding walks on infinite grids
  • Self-avoiding walks
  • Thirty years of the ATCM conference
  • The Aberth-Ehrlich method
  • The Weierstrass-Durand-Kerner method
  • Parabolas, numerically
  • Parameterization of the parabola
  • Four point parabolas
  • General expressions

Tags

MATHEMATICS 21 VOTING 15 JULIA 14 PYTHON 14 COMPUTATION 11 ALGEBRA 10 GIS 8 GEOMETRY 4 JSXGRAPH 4 PROGRAMMING 4 CAD 3 IMAGE-PROCESSING 3 LINEAR-PROGRAMMING 3 ANALYSIS 1 ASTRONOMY 1 CRYPTOGRAPHY 1 EDUCATION 1 GEOGEBRA 1 HASKELL 1 HISTORY 1 HUGO 1 HUMOUR 1 MUSIC 1 ORG 1 SCIENCE 1
What's all this, then?

Copyright  WHAT'S ALL THIS, THEN?. All Rights Reserved

to-top