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Re: evenly spaced vector [message #81394 is a reply to message #81182]

Fri, 07 September 2012 20:40

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

On Friday, September 7, 2012 3:40:25 PM UTC-4, sivan wrote:
> On Friday, September 7, 2012 5:06:48 PM UTC+3, Craig Markwardt wrote:
...
>>>> If you want equidistantly sampled points in *plot* space, then you need to transform to device coordinates first, then do your arcsampling.
...
>>>> Some warnings. ARCSAMPLE uses SPL_INTERP(), which has some overshoot for rapidly varying functions like yours. You may not want that. Also, you used David's original code which sets the endpoint slopes to AVGSLOPEX and AVGSLOPEY, but that assumes that it's still a closed curve. Yours is not a closed curve. For your open curves, you should revert to natural splines where the slope is not specified at the endpoints.
...
>> Yes. I described it above. "If you want equidistant points in plot space..."
...
> yes. i'd be perfect if i could place equidistant points along the curve (isochrone).
>
> you said that i needed to transform to device coordinates first, then did my arcsampling. it seems a little complicated to me. how can i do it?

Read about the IDL function CONVERT_COORD. You have data in DATA space and want to convert to DEVICE space before arcsampling.

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[Message index]

		evenly spaced vector By: sivan on Tue, 21 August 2012 11:21
		Re: evenly spaced vector By: Craig Markwardt on Sun, 02 September 2012 13:46
		Re: evenly spaced vector By: sivan on Thu, 06 September 2012 04:22
		Re: evenly spaced vector By: sivan on Sun, 02 September 2012 07:27
		Re: evenly spaced vector By: Craig Markwardt on Fri, 07 September 2012 07:06
		Re: evenly spaced vector By: sivan on Fri, 07 September 2012 12:40
		Re: evenly spaced vector By: sivan on Fri, 07 September 2012 00:17
		Re: evenly spaced vector By: Craig Markwardt on Thu, 06 September 2012 12:41
		Re: evenly spaced vector By: sivan on Thu, 06 September 2012 10:22
		Re: evenly spaced vector By: Craig Markwardt on Thu, 06 September 2012 07:00
		Re: evenly spaced vector By: Craig Markwardt on Fri, 07 September 2012 20:40
		Re: evenly spaced vector By: sivan on Wed, 19 September 2012 08:41
		Re: evenly spaced vector By: sivan on Sun, 02 September 2012 05:33

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