Started by EigenUser, May 09, 2014, 07:44:30 AM
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Quote from: EigenUser on October 15, 2014, 01:26:24 AMAll this talk on the Boulez thread about how he used the word formant in his own way reminded me of an engineering professor I had a couple of years ago (who is also French) for a graduate dynamics course. He taught us this notation that hadn't caught on in the English language. He calls it "screw theory" and refers to objects as kinematic screws, kinetic screws, action screws, etc. They are basically dual vectors containing (i) a moment and (ii) a resultant. I had no idea where he was getting this from and I couldn't find anything about this online when I was taking the class.Then, one day he tells us "About that term 'screw' -- I made it up!" He explains that there is no English word for what he is talking about and that the French word for these is torseur. To add to the confusion, there is in fact an English theory called screw theory which looks superficially similar, but it is completely unrelated.So, I go home that day and google "torseur". Guess what I find -- an in-depth French Wikipedia article on what this guy has been calling "screw theory"!http://fr.wikipedia.org/wiki/TorseurIt's so odd that there is no information on this in English. I wonder if he is the only one who teaches it in the US. It is a very useful notation, but it was frustrating not being able to find supplemental information on it (though his notes are very clear).Ken (or any other math people), have you ever heard of this? By dual vector I don't mean the dual vector space (you know, with the annihilator, etc.). It is literally just two related vectors written as one object. Apparently it is a Lie algebra.
Quote from: Ken B on October 15, 2014, 10:27:27 AMAll mathematicians Lie about Screw Theory. What you do with your vector is your own business. Or your own kernel, if you are a member of the dual space. Just watch out for idempotence. Never had a problem with it myself but I hear engineers are prone. Just a guess but it sounds like a tensor actually.
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