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  • Educational disciplines: size against market growth

    calendar Jun 15, 2019 · 1 min read  ·
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    Here is an interactive version of this diagram:

    [!APF Figure 4](/APF_figure_4.png)

    (click on the image to show a larger version.)


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  • Tschirnhausen transformations and the quartic

    calendar May 5, 2019 · 6 min read · mathematics algebra  ·
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    Here we show how a Tschirnhausen transformation can be used to solve a quartic equation. The steps are:

    1. Ensure the quartic is missing the cubic term, and its initial coefficient is 1. We can do this by first dividing by the initial coefficient to obtain an equation \[ x^4+b_3x^3+b_2x^2+b_1x+b_0=0 \] and then …


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  • Tschirnhausen's solution of the cubic

    calendar May 5, 2019 · 6 min read · mathematics algebra  ·
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    A general cubic polynomial has the form \[ ax^3+bx^2+cx+d \] but a general cubic equation can have the form \[ x^3+ax^2+bx+c=0. \] We can always divide through by the coefficient of \(x^3\) (assuming it to be non-zero) to obtain a monic equation; that is, with leading coefficient of 1. We can now remove the \(x^2\) …
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  • Colonial massacres, 1794 to 1928

    calendar Jan 28, 2019 · 5 min read · history GIS python  ·
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    The date January 26 is one of immense current debate in Australia. Officially it's the date of Australia Day, which supposedly celebrates the founding of Australia. To Aboriginal peoples it is a day of deep mourning and sadness, as the date commemorates over two centuries of oppression, bloodshed, and dispossession. …
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  • Vote counting in the Australian Senate

    calendar Jan 22, 2019 · 6 min read · voting  ·
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    Recently we have seen senators behaving in ways that seem stupid, or contrary to accepted public opinion. And then people will start jumping up and down and complaining that such a senator only got a tiny number of first preference votes. One commentator said that one senator, with 19 first preference votes, …
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  • Concert review: Lixsania and the Labyrinth

    calendar Nov 10, 2018 · 6 min read · music  ·
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    This evening I saw the Australia Brandenburg Orchestra with guest soloist Lixsania Fernandez, a virtuoso player of the viola da gamba, from Cuba. (Although she studied, and now lives, in Spain.) Lixsania is quite amazing: tall, statuesque, quite absurdly beautiful, and plays with a technique that encompasses the …
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  • Linear programming in Python (2)

    calendar Oct 30, 2018 · 3 min read · linear-programming python  ·
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    Here's an example of a transportation problem, with information given as a table:


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  • Linear programming in Python

    calendar Oct 28, 2018 · 4 min read · linear-programming python  ·
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    For my elementary linear programming subject, the students (who are all pre-service teachers) use Excel and its Solver as the computational tool of choice. We do this for several reasons: Excel is software with which they're likely to have had some experience, also it's used in schools; it also means we don't have to …
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  • A test of OpenJSCAD

    calendar Sep 15, 2018 · 1 min read · CAD  ·
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    Here's an example of a coloured tetrahedron:

    hello
    <div oncontextmenu="return false;"
         id="viewerContext"
         style = "width:640px;height:470px;"
         design-url="tetrahedron.jscad"></div>
    
    <div id="tail" …

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  • The power of two irrational numbers being rational

    calendar Sep 15, 2018 · 1 min read · mathematics  ·
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    There's a celebrated elementary result which claims that:

    There are irrational numbers \(x\) and \(y\) for which \(x^y\) is rational.

    The standard proof goes like this. Now, we know that \(\sqrt{2}\) is irrational, so let's consider \(r=\sqrt{2}^\sqrt{2}\). Either \(r\) is rational, or it is not. If it is rational, …


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  • Recent Posts

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