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Re: disk with hole [message #56828 is a reply to message #56740]

Wed, 14 November 2007 08:08

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

"jochem.verelst@gmail.com" <jochem.verelst@gmail.com> writes:

> Hi IDL gurus,
>
> Has anybody an idea on how to create a disk with hole? So to say, it
> is a circle within another circle and that surface should be filled.
> Thanks to the great website of DF drawing 2 cricles is the easy part.
> But filling the space in between seems to be the hard part. Anyone can
> guide me further?

It's not that hard if you approximate a circle with a polygon.

IDL> th = dindgen(1001)*2d*!dpi/1000d
IDL> c = cos(th) & s = sin(th)
IDL> r1 = 1d & r2 = 2d
IDL> x = [r1*c, r2*reverse(c)]
IDL> y = [r1*s, r2*reverse(s)]

IDL> plot, [-5,5], [-5,5], /nodata
IDL> polyfill, x, y

Also, I think there's nothing stopping you from making this the
USERSYM, and then overplotting it to your heart's content.

Good luck!
Craig

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Craig B. Markwardt, Ph.D. EMAIL: craigmnet@REMOVEcow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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[Message index]

		disk with hole By: jochem.verelst@gmail. on Wed, 14 November 2007 03:52
		Re: disk with hole By: David Fanning on Wed, 14 November 2007 08:12
		Re: disk with hole By: Craig Markwardt on Wed, 14 November 2007 08:08

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