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Re: how to define theta and phi of a sphere in IDL [message #68586]

Sat, 14 November 2009 22:20

penteado
Messages: 866
Registered: February 2018

Senior Member
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On Nov 15, 3:33 am, nisha katyal <nishahans...@gmail.com> wrote:
> No, actually i do not want to define it that way. I want to define
> x,y,z cordinates in terms of r,theta,phi. i.e
> x=r*sin(theta)cos(phi)
> y=r*cos(theta)sin(phi)
> z=r*cos(theta)
>
> I don not kno the difference in defining theta and phi....

Don't you mean y=r*sin(theta)sin(phi)? If so, theta is the angle from
the north pole to the parallel where your point is (90°-latitude), and
phi is the longitude. And David was saying that this conversion could
be done as

xyz=cv_coord(from_sphere=[phi,!dpi/2d0-theta,r],/to_rect)

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[Message index]

		Re: how to define theta and phi of a sphere in IDL By: penteado on Sat, 14 November 2009 22:20
		Re: how to define theta and phi of a sphere in IDL By: David Fanning on Sat, 14 November 2009 22:11
		Re: how to define theta and phi of a sphere in IDL By: nisha katyal on Sat, 14 November 2009 21:33
		Re: how to define theta and phi of a sphere in IDL By: David Fanning on Sat, 14 November 2009 21:18

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