| Re: circles [message #9585 is a reply to message #9519] |
Mon, 14 July 1997 00:00  |
pit
Messages: 92
Registered: January 1996
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Member |
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In article <33C6A55C.E92FBB0D@kprwww.na.astro.it>,
Kevin Reardon <kreardon@kprwww.na.astro.it> writes:
> ;for a circle centered at (150,50)
> xx = rebin(findgen(201,201) - 150,201,201)
^^^
must be 1
> yy = rebin(findgen(1,201) - 50,201,201)
> radial_distance = sqrt(xx^2 - yy^2)
^^^
must be a +
> tvscl,radial_distance le 50 ; displays a white filled circular mask
> The previous suggestion by Peter Suetterlin (pit@uni-sw.gwdg.de) of:
> img = (shift(dist(X,Y),x0,y0)) LT R
> doesn't seem to work if x0 and y0 are not equal to X/2 and Y/2
> (i.e. the circle is not centerted) because of wrapping problems when
> the array is shifted.
Strange, what system/version are you using?
I checked it before posting, and just again on three different systems
(Linux, SunOS, HP-UX) with IDL 4.01 and 3.0.0:
tvscl, (shift(dist(201,201),150,50)) lt 50
exactly does what it is expected to do???
Peter
--
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Peter "Pit" Suetterlin http://www.uni-sw.gwdg.de/~pit
Universitaets-Sternwarte Goettingen
Tel.: +49 551 39-5048 pit@uni-sw.gwdg.de
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