- #1

- 47

- 5

##x=rcos(\theta)sin(\phi)##

##y=rsin(\theta)sin(\phi)##

##z=rcos(\phi)##

##-\pi<\theta<\pi##, ##-\pi/2 < \phi < \pi/2##

but see some people using these instead

##x=rcos(\theta)cos(\phi)##

##y=rsin(\theta)cos(\phi)##

##z=rsin(\phi)##

##-\pi<\theta<\pi##, ##-\pi/2 < \phi < \pi/2##

Have you seen this before?

The second set seems to be "oblate spheroidal coordinates" (http://en.wikipedia.org/wiki/Oblate_spheroidal_coordinates) in the limit where the oblate spheroid is actually a sphere (the argument of the hyperbolic sin/cos is large enough so that

##asinh(\mu)=acosh(\mu)=r=\mbox{const}##

Does this make sense?