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Delen door 2
Een man vraagt aan een goochelaar wat zijn specialiteit is. “Meisjes doormidden zagen”, is het antwoord. “Dat is moeilijk zeker ?” “Helemaal niet, ik kon het als kind al.” “Heb je dan zusters ?” “Jawel, drieënhalf.”
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A History of Pi, Petr Beckmann (ISBN 978-0312381851, St Martin’s Press)
(a history of) Pi first came out in 1970 and the author was a professor of electrical engineering at the University of Colorado. Beckmann fled Czechoslovakia at the age of 14 to escape the Nazis. In the introduction Beckmann states that he could write his own personal history of pi without having to worry about canonical viewpoints held by historians and mathematicians. The book is therefor not a rigorous historical and/or mathematical account of the history of pi. Rather it is an eclectic trip through time making stopping at societies where the knowledge of advanced. It starts with several pre…
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Blaise Logic
“I have made this letter longer than usual because I lacked the time to make it short.” ― Blaise Pascal
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The Taking of the Pelham 123 (1974)
As the title suggests this is about the 1974 version of The Taking of the Pelham 123. Despite being almost 50 years old the movie is still more than enjoyable. It stars Robert Shaw and Walter Matthau as the bad guy and the good guy respectively in the simple plot of 4 gangsters hijacking a NYC subway and holding the passengers hostage for ransom. Most of the movie takes place on the subway car and in the subway control center following how the negotiations between gangsters and the city evolve. New York has to pay 1 million dollars to be…
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Privileged Men
If today someone calls you privileged it may well be intended as an accusation or an insult. Nothing new and unfortunately seldom done with the literary flair of George Bernard Shaw who managed to ‘insult’ a couple of less privileged professions in the same go. “Greek scholars are privileged men. Few of them know Greek and none of them know anything else but their position is unchallengeable. Other languages are the qualifications of waiters and commercial travellers.” ― George Bernard Shaw
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Royal Roads
“O King, through the country, there are royal roads and roads for common citizens, but in geometry there is one road for all.” Menaechmus (4th century BC) in answer to his pupil Alexander the Great asking for a shortcut to geometry.
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Familiar Words From 1974
I started reading {a history of} π again yesterday. I read this some 12 years ago but wanted to read it again as I am going through some algebra fundamentals helping my daughter with her math exams. Almost 50 years ago, in the preface to the third edition from 1974 author Petr Beckmann wrote the following words that have lost non of their relevance : “Meanwhile, a disturbing trend away from science and toward the irrational has set in. … The disoriented and gullible flock in droves to the various Maharajas of Mumbo Jumbo. … Technology has wounded affluent intellectuals…
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Hummingbird
Hummingbird is a 2013 movie with Jason Statham. In the US it was released with the alternative title Redemption. Statham plays Joey Jones an ex special forces soldier with a history. After his patrol is ambushed in Afghanistan and 5 of his comrades are killed he takes revenge by killing 5 random ‘suspects’. He deserts and hides from the army living on the streets of London. One night; on the run for drug criminals he ends up in an empty apartment by chance. He shaves and cleans himself up. Urged by a Catholic nun from the food shelter he used…
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Bombelli’s Methode om Vierkantswortels te Berekenen
De Italiaanse wiskundige Rafael Bombelli bedacht in de 16de eeuw een methode om vierkantswortels te berekenen met een recursieve methode. Als we √n willen berekenen zoeken we een getal a ± r waarvoor n = (a ± r)2 met a een geheel getal en 0 < r < 1. n ligt hierbij tussen de kwadraten van a (bvb. voor 3 is a ofwel 1 of 2 want 12 = 1 en 22 = 4). Lossen we n = (a ± r)2 op naar r dan krijgen we r = ∣n – a2∣/(2a ± r). Met deze formule kunnen we recursief…
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Wondrous Arithmetic : Division
Remember having to divide numbers by hand ? If you have a rational number you can move from fractional form (a/b) to decimal form and back. Going from fractional to decimal form is done by performing the long division method. Going the other way is done using a ‘trick’. Any rational number written in decimal form will either have a finite number of decimal places or an infinite number of decimal places with some repeating sequence. In case of a finite number of decimal places it is simply a matter of removing the decimal separator by multiplying by the correct…
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