[PD] Re: Some VASP questions

Larry Troxler lt at westnet.com
Mon Nov 10 03:22:13 CET 2003

On Sunday 09 November 2003 20:36, Thomas Grill wrote:
> You can either send a "detach 1" message before the first operation, or
> even better, set the "detach" attribute at creation time by specifying e.g.
> [vasp.window @detach 1]. If you have newer vasp and pd versions, you will
> notice that the "@detach 1" disappears, but you can use the properties
> dialog in the context menu (right mouse click) to display the attributes of
> vasps objects (or rather all attribute-enabled flext objects)

<various stuff snipped for your concise viewing pleasure>

> detach

Ok, I didn't know you could do that at creation time - that's what I want.

> > Next, "vasp.window" apparently doesn't handle the "to" message

> vasp.window fills a buffer with a window curve, so a separate destination
> won't make much sense.
> There's vasp.*window to multiply half of a window with some data, or
> vasp.*xwindow for a symmetric version (these two have a @to attribute)

Yes, I misunderstood - I thought that that vasp.window already multiplied the 
existing buffer with its window.

> > Now about the fft stuff - I am not sure what vasp.rfft does actually. It
> the vasp.rfft operation produces the following output
> bin 0 .... frequency 0 component
> bin 1... windowsize/2-1 ... real part of the spectrum (only positive
> frequencies)
> bin windowsize/2 ... Nyquist freqency component
> bin windowsize/2+1... windowsize-1 ... complex part of the spectrum (only
> positive frequencies)
> There's no redundancy of data as expected for a real FFT.
> A magnitude operation has to be performed separately afterwards.
> > IOW basically, for an FFT of a real signal, I only want the first half,
> See the attached patch... it probably does what you want to do....
> best greetings,
> Thomas

Taking a look in 3.. 2.. 1.. 


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