In an ebook about elementary complex analysis I came across Newton's law of universal gravitation with a complex valued function in place of $r(t)$. Can somebody please explain the intuition about how a real valued function gets translated into a complex function $z(t)$? I don't understand how this was done. Thanks! (I think this might be a pretty illustrative way to connect real and complex functions, so I thought I'd put it up.)

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The ebook considers the orbit plane


of the body as a complex plane, and introduces complex coordinates


and complex force


If one rewrites in real and imaginary parts, one recovers the the usual component-wise real formulation of Newton's gravitation law.

  • $\begingroup$ Correction to v2: 'the the' in last line should be 'the'. $\endgroup$ – Qmechanic Feb 20 '13 at 1:09

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