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Re: How to rebin complex array? [message #39013 is a reply to message #39011]

Wed, 14 April 2004 09:31

R.G. Stockwell
Messages: 363
Registered: July 1999

Senior Member

"James Kuyper" <kuyper@saicmodis.com> wrote in message news:407D40F3.F045EC70@saicmodis.com...
> Timm Weitkamp wrote:
> ...
...
>> By the way, there is a good reason for REBIN not to work on complex
>> arrays, and that is the fact that there is not really any proper way of
>> interpolating between two complex values.
>
> Why in the world not?

In the 2D complex space, it is ambiguous as how to interpolate.

Breifly, one could interpolate real and imaginary seperately, as
suggested in this thread. Or one could average the lengths of
the vector, and the angle of the vector.

For any rotating vector time series, component-wise interpolation
will almost always underestimate the amplitude of the interpolated value.

Consider two subsequent values, [1,0] and [0,1].
If this is a unit vector rotating, then the "correct" interpolated
value would be [1/root 2,1/root 2] = [.707,.707]. The componently
interpolated value is [.5,.5].

So it really depends on what the type of time series one has.
It may be that a "norm preserving interpolation" may be required.
(average the lengths of the vector rather than just average components).

Cheers,
bob

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[Message index]

		Re: How to rebin complex array? By: Yunxiang Zhang on Wed, 14 April 2004 13:01
		Re: How to rebin complex array? By: R.G. Stockwell on Wed, 14 April 2004 09:31
		Re: How to rebin complex array? By: James Kuyper on Wed, 14 April 2004 06:47
		Re: How to rebin complex array? By: Timm Weitkamp on Wed, 14 April 2004 00:39
		Re: How to rebin complex array? By: Peter Mason on Tue, 13 April 2004 17:47
		Re: How to rebin complex array? By: Mark Hadfield on Tue, 13 April 2004 17:10

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