John McVirgo
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 Apr 18 awarded Notable Question Jan 21 awarded Yearling Dec 17 awarded Caucus Oct 27 awarded Popular Question Aug 14 comment What is the history of “only if” in mathematics? @BrianM.Scott If a shop keeper said to you: "I will give you this cake only if you give me a dollar", I doubt you would be thinking there were other conditions you may need to fulfill such as having to hand over another dollar. Jul 2 answered Why does $\oint\mathbf{E}\cdot{d}\boldsymbol\ell=0$ imply $\nabla\times\mathbf{E}=\mathbf{0}$? May 14 awarded Caucus Mar 31 awarded Nice Question Jul 4 comment Which simple puzzles have fooled professional mathematicians? Does this demonstrate the calculating brilliance of Von Neuman or him lacking a creative intuition to see the beautiful, elegant solution? I also solved it as he did, but in a few minutes, only to be utterly humiliated by the true solution. Moral of the story - always check for the elegant solution first, before someone else humiliates you with it. Sep 12 awarded Supporter Jul 28 comment Strategies for solving simultaneous equations? @Gerry yes, thinking about it, numerical methods don't actually come into it. Thinking about it more, it's jibberish since I've reduced the $dx$ terms by one, but still have the same number of $x$ terms. Still, I can't help thinking use can be made of it... Jul 27 comment Strategies for solving simultaneous equations? Convert the equation into a differential equation:$\quad dx(\cos x + \frac 1 x) + e^ydy = 0$ and use that to eliminate a differential variable. Solve the resulting differential equation using numerical methods. Jul 26 comment Strategies for solving simultaneous equations? @Thomas well if the functions I quoted are completely arbitary, is it still possible to end up with a function $g1$, even if it can't be written in terms of standard functions of the variables? Jul 26 comment Strategies for solving simultaneous equations? @Thomas Is is really that hard? I think a computer is all that is needed to amke things a lot easier Jul 26 comment Strategies for solving simultaneous equations? @Listing I'm looking at D'Alembert's principle en.wikipedia.org/wiki/D'Alembert's_principle and using the constaints to reduce the number of variables. Jul 26 asked Strategies for solving simultaneous equations? Mar 3 awarded Editor Mar 3 awarded Teacher Mar 2 awarded Quorum Feb 27 comment Derivation of the method of Lagrange multipliers? Very easy to understand, thanks.