oblate spheriod(adsbygoogle = window.adsbygoogle || []).push({});

From http://en.wikipedia.org/wiki/Oblate_spheroidal_coordinates I'm given the formulas to compute cartesian coordinates from oblate spheroidal coordinates.

[tex]

\begin{array}{l}

x = a\cosh \mu \,\,\cos \nu \,\,\cos \phi \\

y = a\cosh \mu \,\,\cos \nu \,\,\sin \phi \\

z = a\cosh \mu \,\,\sin \nu \\

\end{array}

[/tex]

But I've got a few questions:

I've written a short block of code to plot an oblate spheroid:

What isCode (Text):

mu = 0.5

For a = 0 To 100

For nu = 0 To (2*pi) Step 0.02

For phi = 0 To (2*pi) Step 0.02

x = a * cosh(mu) * Cos(nu) * Cos(phi)

y = a * cosh(mu) * Cos(nu) * Sin(phi)

z = a * sinh(mu) * Sin(nu)

Call PlotPoint(x, z)

Next phi

Next nu

Next a

μ? I don't see it defined on Wikipedia's page. I image it is a number that describes how oblate the object is. So I imagine there should be a number I can set it to that gives me a sphere. My guess would be that mu can range from 0 to 1, with one of those limits giving me a sphere.

So I tried it. I see thatμ= 0 gives me a straight line, meaning completely oblate, and the larger I set this number, the more spherical the shape becomes. But it seems to become a sphere atμ= 2, contrary to my guess. Any value larger than 2 gives me a larger sphere. Does anyone know exactly whatμis, and what it's range is?

Also, I see Earth described as an oblate spheroid. What is itsμvalue?

Thanks!!

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# Oblate spheroid

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